I would love to have seen more "small falls" - The math of the fall factor favors bigger falls because there's more rope. But what about falls on the first bolt, or falling past the belayer? Factor 1, 1.5, and even 2 (though don't do with with people!)
Exactly, great question. Think multi-pitch start from a belay point. Or hard falling into the first (few) draws, where you try to shorten rope (if Grigri), drop into the rope, make the fall hard for shortest possible distance (danger of grounder).
@@HowNOT2 For sure, these are good ideas. Using a Grigri will change things slightly, and keep results more consistent, but the biggest variable that wasn't recorded was the amount of rope in the system. Next time I'd recommend measuring the rope in the system for each fall as you can get a measure of how much the dynamic nature of the rope has an effect on the numbers.
www.petzl.com/US/en/Sport/Influence-of-the-belay-device?ActivityName=Rock-climbing You are correct. The increase in slip of the tube style device lowers the overall force.
Since most of the belayer were not anchored. They’re force was pretty much their weight. Different belay devices would be more of a factor if they were anchored. Fun experiment either way!
For large falls the peak forces will depend on the rope more than the belay device, particularly for the top anchor. It is also worth remembering these are relatively small falls with fall factors < 0.5
@@tobiaslilja879something I noticed is the way they were anchored isn't exactly the same as a fixed point belay outside. In real life, the belayer absorbs the force a lot more.
The ropes are durable and just like the ones at the gym. ua-cam.com/users/postUgkxTFxba6lNeHrZaHoY_LXe6ZzmMfaipnwu Caution: I bought the 50 feet ropes and they are long and heavy so make sure you have the space (I do have the space). If I was to do it again I would probably get a shorter version as 50 feet (25 feet each side) is a little long.
Ryan, as a ~330lb climber I would be very glad to see some experiments with somebody my size. My gear fear continues because seeing tests with people that weigh half of what I do doesn't fill me with confidence that I can ever lead climb safely.
i actually have a co worker who has started lead climbing at 280 and although we havent done force tests, i believe you can also do it safely, especially if you are not taking huge runout whips or trad climbing
F=ma, meaning if you double the mass, you double the force. so if a 150 pound climber generates 2 kn, a 300 lb climber generates 4 kn from the same fall. still plenty low enough for all the gear in a gym.
There is a very well presented grabbing instinct by the falling leader which additionally lowers the reading on his dm because he happens to grab above it. Worth pointing out.
Grabbing the rope or gear is a habit that everyone should break. A friend grabbed the rope while falling and lost a finger! But not while I was climbing with him...
Watching this makes me feel so much better climbing outside. It turns out that it's pretty hard to generate an amount of kilonewtons that threatens even basic gear's tolerance. Good to know!
The integrity of the gear is one thing. To place and use it PROPERLY is the MAJOR factor, and there's plenty of ways that can be done so your gear pulls out at far lower loads. In fact, if the belayer is too far back from the rock, simple tension on the rope can lift pro out of well placed positions (particularly a nut placed for a downward pull. I've seen that too many times on the beginning of Double Cross in Joshua Tree just b4 the crux! The lead climber steps up into the crux and the last 2 placements pull b4 they get into the crux! The day I finally had the juevos to lead it we walked up to the base of the climb and there was a huge blood stain on the rock at the base. Bad juju that day. Walked away from the climb. Hell, the rock can break too! I had a chunk come off on a roof I was really yarning on in Aspen. I came flying off penduluming off the piece I placed and came slamming backing a pointy rock - which luckily hit me right on my chalk bag! I was damn lucky on that one!
For the question why the forces don't add up I was instructed that the friction in the draws and the elasticity of the dynamic rope help absorb part of the energy. As for suggestions. I've plotted all the data you provided, including climber and belayer weight, and did not find any correlation to the results. I think there are more variables than considerate. Some things I would do trying to get more consistent data: 1- Have the climber fall when the knot on the harness gets to a reference point, this would mitigate any problems on having more or less rope on the system depending on the climber height. 2- Have the belayer positioned always on the same spot, same justification as above but now considering his position toward the wall. 3- Guarantee that the belayer has a standard slack/no-slack amount of rope on the break. Same as the two above. 4- Measure how much rope is the the system from the break till the climber. Having the estimated fall factor might help understand the trends. 5- Have more than one fall for each test, average or deviate the numbers so there is more consistency to the results. 6- Have tests where the climber is lighter than the belayer. This situation is very common and might look more a static fall 7- Try different setups with less or more draws in between. You can never have too much data lol 8- Rope technical information. We can add the elongation on the math and try to determine the influence on the rope on the system. I think that with this much information we can try to determine between fall distance or weight difference which contributes more to increase the load, as well as any correlation with the fall factor and how much impact does having more or less draws has the in the system. I weight 211, and always feared that when I fall I was pushing more KN than that. Is good to know that I can still add more load on the rope before snapping it. Like I said before, what you are doing here is extremely helpful to the community, if I can help on any way just let me know.
Vitor Viotti thanks! I think it would be nice to get a usable model so you would be able to predict within half a kn what you are generating. We will brush over many unanswered topics in climbing then go back through with a more scientific approach for sure.
@@HowNOT2 You could minimize the friction by only being clipped in to the last bolt. Maybe setup a locking one for the last one and unclip the rest. I say minimize because I'm not sure how the rope drag on the last draw will factor in
All excellent advice. The largest confounding elements are almost certainly the length of rope in the two halves of the system and the friction from the draws. It would also be interesting to see the net accelerations applied to each side of the system (falling climber, and belayer). F = ma, so should be easy enough to figure out.
Also, the numbers will only add up if all three dynos experience their max load at the same time. This won’t be the case due to the friction and the dynamic rope. The climber’s dyno will experience max force at the moment that his side of the rope is at max extension, the belayer’s will be at the moment (later) when his side of the rope is at max extension (likely the moment he leaves the ground), and the anchor will be somewhere in between.
This was awesome. More please! As to why they don't add up, - work done by friction - difference in catching "softness" - amount of rope to increase the time in the equation of (Force × distance)/time there by decreasing the amount of dynamic peak loading
I wish I could subscribe and thumbs up twice. This is exactly the kind of testing that the climbing community needs. Just knowing that big falls and small falls only produce relatively small fall factors (relative to gear ratings) is so confidence inspiring. Some comments below talk about ways to improve the scientific aspects of these experiments by isolating various features, adding limiting knots, etc. with worries about energy and momentum conservation. Unless the goal is to create a model that can predict within half or a tenth of a KN, which seems impractical in the field, then experiments like these have the correct approach: test high probability fall scenarios. There are definitely 'classic' routes that are super run out, where higher fall factors can occur, but in most sport and even trad settings, bolts and gear placements are close enough together and in relatively secure places. I would love to see you guys continue this line of inquiry!
It's important to note that this video only tested small fall factors (as defined by UIAA, fall distance vs. rope between climber and belayer), and higher fall factors can occur (and indeed, are more likely to occur) with less rope out, which means that forces can be much greater than measured in this video; less rope between climber and belayer means less stretch distance, which means higher impact force even if the fall distance is the same.
No experience in Climbing, climbed once in highschool when i was a kid, never slacklined, still watching your videos anyway, for the science, and the logistics insight !!
I feel like there aren't any good videos explaining fall factors, and that type of content would suit this channel really well. I bet you could make a video MUCH better than what's out there right now.
Jo69 there are a few videos on falling and types of catch and their effect on the climber by the UA-cam channel “Hard is easy”. (It used to have another, imo better name). It would be nice to see more though.
I weigh 245 lbs, I’d love to see what kind of forces my weight places on the gear! It’d be real cool to see if it’s graphable on scale with weight/height of fall. I also climb with an Edelrid ohm, because most belayers weigh less than me. Have you thought about testing these out to see what kind of load/force reduction they actually make for the belayer?
And since the belayers weigh less than you, you need to anchor them so they don't get pulled through the first draw. Would love to see the forces in that case as it's a worst case scenario. 245# isn't unusual when you have a rack of gear.
The length of the fall isn’t a good measure of severity of fall. Their longest fall was actually one of their least severe. A much better measure is fall factor which is (fall length)/(amount of rope between belayer and climber). fall length is the length in free fall, the distance the climber falls once the gear is weighted doesn’t count. None of these falls was > 0.5 so they are all minor. Their “long fall” actually had a lower fall factor than their typical falls. The “Z” fall was the worst because the rope drag effectively reduces the length of rope in the system. The worst fall in a gym is from bolt 3 onto bolt 2 with a FF of ~0.66 which still doesn’t rate as serious. The gear is designed and tested for a fall factor of 2 i.e. a fall from above the belay to below it with no other gear on a multi-pitch climb. Which is why good trad leaders like to get gear close to stances, preferably before leaving on snow/ice/alpine.
We once dropped a controlled 20kg weight on a brand new petzl helmet It dented! The exact same model helmet with 5 year's outside use smashed to pieces in the same test. It's always worth keeping a thought on how much sunshine your kit has absorbed plastic degrades under uv light over time. Great video thank you 👍
For the forces to add up you would need 0 friction (or remove all other quickdraws before dropping) , both belayer and climber to pull on the quickdraw in the same direction and the peak force exerted by the climber and belayer to happen at the exact same time. Not all of those things happen, but its very nice to see the actual numbers rather than the rule of thumb calculations for once. Great video!
Molo Mono yea. Eliminating variables is what so many experiments do. I love throwing in all sorts of monkey wrenches in it to see the range of what we get in the field in real life.
I love this video. it really backs up why you'd want to use 3 cams for a trad anchor, coming and finding some ball nuts fail at 3.9 kn. Really loved being able to see all the number side by side
Probably already mentioned by others, and just a basic observation (worth testing): with the rope forming a continuous translation of forces through the top bolt, the force on the bolt at impact should be approaching double the force acting on the climber, much like a pulley block with a doubling action except with greater frictional losses, dampening losses through elongation of rope and also a loss through the dampening reaction of the belayer moving in reaction, so this looks great. You'll soon have more real situation data than the climbing manufacturers! :)
As a tree climber i find these videos interesting. What you guys are doing in these tests as experiments reminds me of lowering sections out of a tree. In tree work, climbing we "never" climb above our tie in point. The tests you were doing we would refer to as locked off negative rigging. I've cleared a fence when lowering (belaying) a piece and a pulley was being used instead of a natural crotch which has friction. When the pieces being lowered are to heavy to handle without adding friction we either take wraps on the trunk of the tree, or use a friction device at the base of the tree. When possible we always prefer to let it run to reduce dynamic loads on the tree and ropes. There are some really cool videos out there of rigging, both just showing and instructional. Stay safe, and have fun :) P.S experience ropers are highly valued in tree work, as a climber there are times i have to trust the person on the rigging ropes with my life.
Great video, love what y'all are doing!!! I would love to see some tests on factor 2 falls. Very applicable to the climbing community, and I'm sure it would pull in more viewers. Thank you Ryan and team!!!
Thanks for the video guy's. I would have liked to see a slightly larger climber, maybe 200lb's or 90kg. I would have also like to see double ropes put to the test and some trad protection, nuts rather than cams. I really appreciate what you have done so far and keep up the good work.
why? force vs TIME? Makes no sense at all.Its based on the amount of rope in the equation. Dynamic rope stretches. The more played out, the more it stretches and less fall factor.
This is awesome! Exactly what i needed to see! I did some mathematical simulations in the past to see how this all worked. But was never shure about the actual forces due to friction (especially all quickdraws combined) and rope elasticity due to ciclic loading. It changes over time and after heavy falls, rope needs time to reset. The equalization and highline anker video's were enlightning as well, though the forces are applied in a swelling manner, instead of an abrupt way. This will most definetly have some effects. Ideas: - Film with a thermal camera. (Here in the netherlands we can rent them.) This could visualize the heat very intuetively. (quickdraws, belaydevice and rope!) Request: - Using these measurement devices in a climing anker. (i know, the lines are to short for that, but i've seen you being creative before! ;) ) - Dropping a load of a (WAY TO HIGH) location. Perhaps using some old discarded climbingropes to see where they would break. The knots or the anker setup. Notes: - If you need any help with calculations, I might be able to help ;) THANKS!
@@HowNOT2 It's a literal translation from dutch climbing literature but he's talking about the differences between belaying from the anchor, or belaying from your own harness with a quickdraw in the anchor to redirect the rope. The 2 common types of multi-pitching belaying.
Your climbing gear is rated for KN, kilonewtons are how forces are measured, LBF is such a misleading way of measuring forces since the same weight can generate all sorts of numbers. I want to compare KN with the gear so we can make good decisions based on the gear we have. Its 224.804lbs per 1KN btw
@@HowNOT2 I think he was referring to using kilograms for when weighing the people cause the rest of the works besides ghana (IIRC) uses kilograms to measure weight. As a scientist, *face palm* I mean ffs, even the British who made the imperial system isn't using it anymore As an American doe, AMERICA. F$@# YEAH!
@@marcushausch except when it comes to multi billion dollar science projects we send to Mars... then we mix up the units and waste billions of tax payer dollars.
Very good video. 1.- Answering the question about why the addition of belayer and climber forces don't equal the bolt. Lot of energy is released stretching the rope and heating the friction points. 2.- It would be nice to see another video stopping falls with a static device like petzl grigri, I presume forces would be quite higher at all points. That's a very popular device in sport climbing that may, or may not, be used in other contexts.
Some work is done on the rope to stretch the rope itself, so the rope essentially distributes the forces throughout. There is still conservation of energy but some of it is lost between the measuring devices to the rope itself, which is why the belay/climber readings dont sum to the bolt.
1. Please try to register full graph from enforcer, not just peak force 2. For us European, refer mass in kg as well (I’m glad you’re into kN :) ) 3. Tests I would like to see: same FF, different fall distance (again, full graph); pendulum vs vertical fall of the same fall height; short fall distance, freshly tightened knot vs after multiple falls; static mass vs climber. 4. Thanks for great video!
You should add a dynamometers to each quickdraw. Them are acting like little belayers. That is why you miss some forces at the belayer but more or less you have 2*climber at the bolt. Interesting to note that from 1.5 to 7 (in the Z) times of the climber force is absorbed by the quickdraws.
New to the channel, really like it! The figure of 8 tightening must be a factor in the load measured, meaning the second fall will have a larger load due to less load reduction, J Marc Beverly wrote a good paper describing this effect
Something I'd like to see when you're next doing this: clip a sling into the load cell and see how much force you can generate by bouncing on it. I've seen it suggested that when learning to place trad gear you test your placements by bouncing on them; it would be interesting to see if that generates forces comparable to a fall.
I've climbed a few big walls and bounce test the gear. Instead of using a sling, you should use aiders. This should be harsh since aiders don't have much material to absorb forces. An interesting thing that happens when bounce testing is some placements that you think will barely hold end up surviving vigorous bounce testing. Of course, placements that look bad are bad, The biggest benefit of bounce testing while doing aid for me is it improves my confidence in placements when I'm free climbing. It provides real experience in judging placements.
@@WyomingMtnMan My hardest aid was ancient history - pre-cams. It taught me loads about placements, but bounce-testing done correctly only loads slightly above body weight, what a very short, soft fall would impart; this is useless in regard to what forces solid protection and anchor pieces must hold. The theory is if the next piece fails under its bounce, the previous one has already proven (barely) sufficient to catch you; once a good bounce is held, you move gingerly and repeat the process. A series of marginal placements provide at least the illusion of confidence, in this principle, but the most common mistake is never totally transferring 100% of their weight to the tested placement; any residual weight on the foot in the etrier clipped to the lower piece reduces the force on the tested one, and if you then commit and begin to move up, that extra few pounds may reveal the piece wasn't good enough, after all. By then, your two or three feet of vertical adds a tiny extra force if it pops and you fall onto the previous one, perhaps exceeding what it held in its bounce test - from there, you may enjoy the legendary "zipper" fall, which is perfectly named. Just hope no ledges come to play before something eventually catches you!
Why is belayer KN + climber KN < bolt KN? Belayer and climber both enjoy the benefit of rope stretch and friction while the bolt does not. Note that in general, twice the force at the climber is close to the force at the bolt Mel's Long fall climber force 1.78 x 2 = 3.56; force at bolt 3.54, a difference of 0.02KN, greater on climber side Mel' Small fall climber 1.26 x 2 = 2.52; bolt 2.88, difference 0.36, smaller on climber side TJ small climber 2.14 x 2 = 4.28; bolt 3.72, difference 0.56, greater on climber side TJ long 1.73 x 2 = 3.46; bolt 3.46, difference 0.0 TJ static 2.65 x 2 = 5.30; bolt 4.52, difference 0.78, greater on climber side Mel + vest 2.34 x 2 = 4.68; bolt 4.06, difference 0.62, greater on climber side Ryan Z drag 2.43 x 2 = 4.86, bolt 4.78, difference 0.08, greater on climber side Ryan K big 1.87 x 2 = 3.74; bolt 2.6, difference 1.14, greater on climber side
One big issue with this test (aside from the lack of measurements of fall height, rope length, etc.) is the placement of the dynomometers on the climber and belayer. If you watch at 6:17, you can see the climber grabbing the knot above the dynomometer, which cancels out some of the force in the rope. The belayer also does this when pulling the free end of the rope to add friction. Most of the results from climber and belayer add up to around 700 to 900 N short of the force felt at the bolt. This is about ~190 lbs. That 190 lbs is easily explained by the users pulling above the meter. This could be improved by placing the dynomometer 5 ft or so away from the user. The method of measuring done in this video shows how much force is on the harness attachment point, which is slightly less than the force on the rope because of the user pulling on the knot. This could be useful, but you might aswell find the force in the rope as I suggested above in order to find a worst case scenario if the user does not use his hands at all.
Could you test different knots for tying and their relative breaking strength/slippage under load? Considering different dynamic rope breaks at different forces, comparing them relative to reach other on the same single rope would be sensible. Was thinking of comparing: Rethreaded fig 8 Rethreaded fig 8 + barrel knot stopper Rethreaded fig 8 + Yosemite stopper Single bowline Single bowline + barrel knot stopper Single bowline + Yosemite finish Single bowline + Yosemite finish + barrel knot stopper Rethreaded bowline Rethreaded bowline + barrel knot stopper All when loaded normally (as when taking a fall) and again when loaded 90 degrees off the normal orientation of load (as when you're clipped into an anchor and catching a fall whilst belaying off that rope's loop). Love the videos and thanks!
Rope access people have a general rule that any knot gives 50% reduction in rope strength. There are so many variables included that it's almost impossible to give consistent results otherwise and they are generally fairly close. If you go for 50% you won't go wrong.
Do one showing the strength of guide ATCs? I cant seem to find ratings on them however they are made to be clipped in directly and take the same force the carabiners would normally take it seems? But they don't how a rating on them.
In my previous post I stated that the bolt force would always be twice the climber's (faller's) force. However, this is only accurate under ideal conditions: 1. The climber's and belayer's ropes are parallel to each other. (both pulling in the same direction). 2. The climber is falling directly below the bolt/pulley. The reasons your bolt forces did not follow this formula (bolt force) = 2 X (climber force) was often due to the quick draws adding friction and creating angles between the ropes. Also the line of fall was often not directly below the bolt/pulley. This new formula allows for the variable of rope angles to be considered. Pulley/bolt force = 2 X (climber force) X cos(angle/2) I did the calculation and found it to be a fair match with the data you provided. In my calculation I used rough estimates of the angles I observed between the ropes during the max pull of the fall, which changed from one event to the next. In the Ryan Big fall, the angle between the ropes was far greater than all the other events. And the fall path even more out of line with directly below the bolt (causing a lot of swing). Swinging into a lower elevation has much lower accelerations than falling straight down until you hit the end of the rope. Summary: The odd rope angles and frictions in the system tend to redirect and distribute the forces (created by the falling climber) away from the bolt, and into other parts of the rock (attachment points of the quick draws). What the experiments do demonstrate is that the forces on the ropes and bolts are complicated to calculate and affected by a host of variables (I noticed at least 10 contributing variables). We also have shown with data and calculations that: 1. The pull on the bolt will never exceed twice the pull on the falling climber. 2. The pull on the belayer will max out at a force equal to the force on the falling climber. 3. Increasing friction increases the forces on the bolt and climber, but reduces the force on the belayer. 4. Increasing the angle of the climber's rope relative to the belayer's rope reduces the force on the bolt. 5. Falling from a point not directly below the bolt results in less force on the system (bolt and climber) FYI: in Mel's small fall the bolt force is more than double the climber force. I believe this was a result of Mel grabbing the rope above the force meter, so the meter did not read all the force on the falling climber. (this may have happened during other falls as well).
Dan Gillam I’m afraid your analyzing it as a static’s problem when this is a dynamic problem. this idea that the net force should come to zero is only true for non-accelerating systems. Since the faller has to come to a stop, there has to be a net force in the upwards direction to create that acceleration in the upwards direction, and the extra force from the bolt is providing that extra force in the upwards direction. This is described by Newton’s second law
Bolt peak force would only be double the force on the climber if there was 0 friction at the bolt. If, for example, friction was near 100%, you would have the same force on climber and bolt. Even if the angle is 180 at the bolt. (Maybe that’s what you are saying and I misunderstood, sorry if so!) 😀
@@adamlightman8953 The rope pulls up on the climber, and the climber pulls down on the rope. If there were no rope in between them then these forces would always be the same. (this assume no pulley, just a climber tied into a bolt. Even with a stretchy rope the force down on the bolt end of the rope will nearly equal the force up on the climber end. There is a net force on both end objects. The climber is accelerated upward, and the bolt/Earth is accelerated downward. In the video there are a lot of other things pulling on the rope, so the situation is more complex. Also there is a delay caused by the stretch rope (the pull down at the top does not happen at the exact same moment as the pull up on the climber, consider the pull to travel through the rope as a compression/longitudinal wave). The impulse at top and bottom would be the same (impulse = force X time), but it is possible that the force at the top was lower magnitude for a longer time, and the force at the bottom was higher magnitude for a shorter time. Newtons laws apply to all situations, dynamic and static.
@@johnliungman1333 That is true. In a situation where the climber is tied to the bolt (100% friction), and there are no other attachment points. When you introduce a pulley into the system you also introduce a bunch of other attachment points, and the downward force ends up being distributed and redirected. Theoretically if you could measure all the downward pulls (impulses) on the wall, and all the upward pulls on the rope ends they would sum to zero. Having a pull on the other end of the rope also tends to make the climber's pull go to the side, so that the force meter is not in line directly between the climber and the bolt. Then it would take a vector force analysis to determine the component of the climber rope force that was acting inline with the force meters (which is what the meter measures).
Some suggestions: I would love to see a comparison of different Fall factor Falls. Lets say a fall after the first bolt and a big whipper from the top. Also could you test a massive multipitch lead fall where the climber falls below the belay? DIfferent Falls on different belay devices would be great also to check out the difference for a grigri belay vs. atc in trad. Keep up the nice content!
Excallent video. The answer to your question is that there are forces generated by the fall and the catch that cannot be absorbed by the system (belayer+belay device+rope). The only instance where the exerted force is lower is when you have a long stretch of rope that can absorb the force of the fall. In the big fall the forces of the climber and the belayer add to 2.71 kn and the bolt reads at 2,60 (-0,11) The more static the fall the higher the reading for the bolt is (z- drag and static fall) I see that you belay with an atc, which makes a pretty soft catch. Could you do the same tests with a gri-gri? I think the forces generated by the autolocking devide will be higher on the bolts. Thank you very much for this very interesting video; I´d like to point out that most tests are done by throwing down a weight that doesn´t resemble at all the way a person falls and tend to give results that can hardly be extrapolated to real climbing, yours on the other side does it as it should be done. Thanks again
Having a dynamic belayer helps reduce the force by adding "virtual" stretch to the rope, and more time to decelerate the climber. In a high friction pulley (carabiner), the climber's force would approach the force created by a rope tied to the bolt. However the force would still be less due to the slip of the rope around an pulley in an anchored belayer system.
This makes me feel so much better as a rope tech that my gear is designed to take over 8x times the shock loading of the hardest fall here. The force required to actually break my gear is equivalent to forces that would literally shatter all of the bones in my body lol.
Places were energy is being lost and not meassured, explaining the difference. - Rope drags on the quick draw would heat it up, which would not be meassured. - The rest of the quickdraws on the route, which where not meassured. - Rope absorbs some of the energy of the fall, by streching.
If belay device was grigri, I think force on belayer's dynamometer would be higher (because belayer's hand takes more force with ATC), also friction on quickdraws reduces force on the main bolt. It will be interesting to test other fall factors as well as top rope.
Friction on quickdraws does reduce the force on the top bolt (pulley), while more friction on the top increases the force on the top. You could further reduce the force on the climber by using a low friction pulley at the top, but you better tie down the belayer so he does not get pulled all the way up the mountain. The more slip (less friction) in the system (belayer or climber) the less the forces will be. More friction means more force on the ends of the rope (climber).
@@HowNOT2 the way how it is belayed has definitely a huge effect on forces... www.petzl.com/US/en/Sport/Influence-of-the-belay-device?ActivityName=Rock-climbing
Hey Ryan, we'd love to see more tests with climbing gear here are some ideas from my end: - Edelrid MegaJul how much is needed to break this device? it look weak (and is cheap in testing because it not expensive) - Quickdraws: my (online)research showed that most of them are barely over the mbs - Friction until burn is this possible? e.g. a 100m rope with e.g. 100kg and high friction on the belay device (e.g. tube) use 99m and stay on the last meter, is it so hot that it burns trough? - zig-zag belaying in case the belayer weight is much less than the climbers weight: what could go wrong?
The rope NEVER passes directly thru a runner. The rope only goes through the binder and belay device, so the runner is never involved with any friction or heat. Your belay device may get very hot on a long rappel, but any portion of the rope is only in contact with it as it passes thru on your way down.
I'd like to see a test of a leader fall that zippers out a few questionable pieces of protection. do the first couple of pieces take enough of the force to allow the 3rd piece to hold the fall? Also, how good does an Ice screw placement need to be to catch a screamer?
Why do people ask such ridiculous questions? You want them to purposefully place gear to fail andthenjump on it for your entertainment? And why would you ever even think of testing an ice screw if it's questionable at all? You do realize that cli.bing isn't a game dont you?
Would love to see same tests done with DMM revolver. There was a big math argument years ago among mechanical engineers and I’ve wanted do this test forever. The question being, using a revolver would lower or raise the force seen on an ice screw or crappy trad Cam placement? It looks pretty clear though that: Higher friction in the rope *after* the top carabiner = higher force. What about @ the carabiner? Seriously. I’ll doordash beer to Sacramento for you guys doing the test. (With enough notice I might even drive up and bring the beer myself!) HMU.
This is what I want to know as well. You have arborists designing devices to add friction at the top and reduce mechanical advantage and climbers reducing friction at the top in an attempt to reduce fall factor! Which is it? Or is there just any appropriate amount of friction..
sorry if i'm bombarding your post! but i'm thinking this through further as i am doing the washing up. i have a thought that small falls with heavy weight might benefit from more friction but at a point there is an inversion and the light weight big fall brings the fall factor into focus. i imagined arborists and climbers both looking at a spoon from different sides(!! :) )and seeing a reflection right side up and upside down with the focal point just to one side. No i'm not smoking anything. I would guess a small slump onto a microwire might fit my first catergory. No maths to back this up, hope someone can put us straight.
Neil D My thinking is that the peak force always gets clipped as the weight of the belayer comes off the ground. (Which is where all the math I’ve seen missed. They assume belayer is infinitely heavy.) So in a zero friction system the peak force is only limited by the amount of time it takes to accelerate the belayer (which should be some time constant based off the stretch of the rope/fall factor/meat squishy ness/harness, etc. In any ice climbing/micro trad piece where the fall must hold the weight of the climber, I’d rather it lowered the peak force on the piece.
Very interesting - thanks. There are lots of tricks used to reduce shock loads on trad gear: use of half ropes rather than singles, "soft" catches, revolvers / screamers on marginal gear, equalising pieces or clipping them to different ropes etc. It would be great to see some data on whether these actually work
I think the total force on the top bolt is the sum of belayer force, climber force, AND drag on all the bolts below which is where I think the missing force is going. (hands off the rope during the fall would possibly help generate cleaner data.)
@@HowNOT2 I'm an applied math PhD student and between you guys and some video analysis and models put up by "Hard is Easy" I'm starting to get curious about further mathematical modeling of lead fall dynamics. More data more better =D One other thing you could do is put a fixed camera across the room perpendicular to the plain containing the climber start position - end position - and top quickdraw, to record the falls. Would enable video-analysis to find position of the climber at each time, i.e. their acceleration and trajectory. Bonus points for having a meter-stick in the same plane to help scale the distance.
The reason Bolt does NOT equal climber + belayer. The belayer and the climber both pull down on the bolt/pulley with their indicated forces. However friction with the "pulley" causes the pulley to pull up on the rope (and thus the rope to pull down on the pulley, Newton's 3rd law of motion). It is the frictional force that causes the discrepancy between the force on the belayer and climber. The amount of the friction must therefore be equal to the difference between the pull on one end of the rope and the other (discrepancy). The total down force on the rope is equal to the sum of the climber and belayer, plus the pull created by friction. Climber force minus belayer force = friction Friction + climber+belayer = total downward force on pulley. Here is one example from your data. (1.78 - .99 = .79 friction) climber + belayer + friction = total .79 + 1.78 + .99 = 3.56 theoretical total (actual measure total was 3.54) FYI: you can also get the calculated total simply by doubling the climber's fall force. 1.78 * 2 = 3.56 FYI: using a low friction pulley would decrease the difference between the belayer and climber, but the formula would still work. In the absence of friction the belayer and climber would be equal, and their sum would equal the bolt. However, you would never be able to have a 100% efficient pulley due to the internal friction of the fibers as the rope stretches and bends. FYI: I am a high school physics teacher, and hobby climber (top rope and TRS only).
dynamometer on each bolt will give a closer sum of forces. Since all the bolts help to distribute the weight of the climber and belayer then the entire system needs to be included in the free body diagram. It is true that the top and bottom bolts will see the most forces; however, two test points only allow for assumptions to be made and not create an entire sum of forces.
Long & short falls: in spite of the length of fall, more dynamic rope to extend the period of application in the long fall and constrain the forces on the bolt and belayer so not major differences in the pattern of forces. Static fall: pushed the numbers up by introducing rgidity into the system. Z Drag: made the friction do the work to protect the belayer but in doing so prevented the entire length of dynamic rope coming into action which would otherwise have reduced the force on the climber and the bolt. Big fall: the force on the bolt is reduced because the climber and the belayer are not applying forces to the bolt in the same direction because the fall is at right angles to the line of the rope. (Thought experiment: if he had left the roof and started climbing down the other side then a bolt placed there would have seen almost zero load.)
I haven't seen much on the physics behind the measurement, so here's a try. First of all we see, that the climber falls into the rope, that attached to the anchor. On the other end of the rope there are some quickdraws and the belayer. So belayer + friction in quickdraws = force on climber. This explains most of the results: the force on the anchor is approximately double the force on the climber in all cases, because the anchor holds both ends of the rope. The belayer doesn't experience the full force because the quickdraws on his end absorb some force due to friction. Last but not least we must explain the minor differences in comparison to this theory: As mentioned in the video, only the maximum force is measured by every dynometer. But what really had to be absorbed is the energy of the falling climber. Physics tells us E=F*s (Energy equals force times distance) (Precisely this is an integral, which leads to nontrivial mathematics) So if the climber has less rope stretch on his end, his energy is absorbed over less distance than the belayer uses to absorb the energy, resulting in yet a lower maximal force on the belayer's end of the rope. Thus the force is more equally divided and we measure a less high peak force.
I'd like to see this same experiment with the Elderid Ohm incorporated with its own meter to see how much force it really does eliminate from the rest of the setup.
I just have to ask "why"? It won't make any difference in how or what you climb. IF YOU INIW WHAT YOUR DOING, any device, and even no device ( hip belay) will catch a fall. They've been doing it for decades.
I'd love to see a dynamometer on a cam(of different sizes) catch a whip outside (backed up with a bolt below) and see what kind of forces it has. Curious if they're less or more than the bolts in a gym.
Colin Woodside Just think about it, If you fall from the same height with the same rope and slack it doesn’t matter at all how you are connected to the wall, the only difference will be, that the cam might pop out, the force is still the same.
The force of the fall is also being distributed along all of the hangers you clip into as the rope drags through the carabineers therefore decreasing the amount of force the belayer is experiences
You teased us with "you'd be shocked with how little it takes to break a dynamic rope". In another video I think you had a rope from the 90's break at around 12kn, maybe? I was wondering if you could do some climbing ropes with different amounts of slack in them, as the weight is distributed along the rope in the event of a fall.
To describe the difference in forces at the bolts, relative to the sum of the forces at the belayer and climber, you must think in terms of inertia or energy. Both would give the same result, but would paint slightly different pictures. The bolt absorbs the energy that the rope cannot. Or in terms of inertia, the total force is equal to the changes in momentum of the climber and belayer, divided by the time of the interaction. Inertia and impulses are (in my opinion) the best ways to carry out a dynamic analysis of most climbing falls. But sometimes energy principles are slightly more simplistic.
I’d like to see the worst case and best case. Worst case is probably a heavy climber’s factor 2 fall from above a belay station when belaying from the anchor with an assisted braking belay device. Small nuts are only rated for 4kN, would be interesting to try it on them. Best case is probably a top rope fall or a follower fall on a multi pitch route. Would also be very interesting to see how much softer the fall is with a half rope (and how much harder the fall is with two half ropes).
Most people are concluding how hard it is to generate a large force, focusing on the people (belayer and climber). I’m a trad climber and expect/require my belayer to be anchored on multi pitch routes, that test did increase force by reducing the dynamic absorption/offset occurring when belayer is pulled upwards. My focus then goes to the piece of gear catching the fall. Seems 5-6 Kn is going to be common. Some gear is not much more than this AND some placements are definitely a lot less than this. How and what gear you place therefore becomes the most important factor (if that isn’t overstating what should have been obvious to all of us, even before this test). I’d like to see more on forces on trad gear in different types of placements. Maybe on a Big Wall 😀
Brilliant video! I’d love to see how a pulley carabiner helps with force at the bolt. Also how a fresh rope compares with a “tired” rope (one fallen on multiple times)
We did test an old rope but didn't include it in video because it didn't really change anything and too much data in one video dilutes what we had. We will specifically test this later after we trash a dynamic rope and make it lose most of it's dynamic properties.
@@HowNOT2 It wasn't old rope but new rope that had been fallen on a few times rather than new rope that was fresh... Nice to know that older rope is still bouncy though :-)
@@neild7971 if it goes round something it's a pulley. A more efficient pulley will reduce the load on the climber and increase the force on the belayer. The force on the gear (quickdraw, nuts, etc) will be reduced also as the fall factor is reduced
@@largeformatlandscape are you sure the force on the gear is reduced with a higher efficiency pulley. any info would be appreciated as this interests me.
Would be cool to see the forces when hauling on the bolts/anchor and hauler with multiple bags and portaledges. Also the working load forces on the pulley's with a mechanical advantage systems of 2:1 and 3:1.
The peak force on climber + belayer does not add up to force on a bolt, because dynamic rope makes the force more spread in time. If you would calculate integral (sum over the whole fall) you would get the same value. Basically, due to elasticity of the rope climber decelerates faster than belayer accelerates.
I think the bolt experienced more force because it is solid and can’t/won’t move when the fall happens, thus there is no force absorbed as there is for the belayer and climber due to stretch of equipment and the non-static nature of their anchoring.
Great video, informative and really useful. I'd very much like to see some results for heavier climbers (220-250 pounds for example) and to see the results of Mike 2.0 taking the first fall but with a fixed belayer and him taking the larger fall from the top of the gym. Finally (and this would require a bit more ropework to safely set up, it would be very interesting to see the results of taking the same length of fall onto a shorter length of rope by having the belayer belay from a hanging on the 2nd bolt (and off to the side for safety) and the leader take falls from the 4th bolt as they did in this video and ending up hanging well below the belayer. Your simulations are great for showing how forces develop in a normal day-to-day climbing fall but there are many times when climbing, particularly outside, that you have to push the boat out a little bit, run out further, rely on gear that is well below you or climb as a heavier climber complete with 10 pounds or more of kit with you (consider ice climbing kit as an example). It would be useful to see what happens to those fall forces when you push the envelope a little bit.
I'd like to see the force on the climber with a static fall, where the belayer can move up to 2 feet before the belayer's anchor takes up tension. The belayer does NOT attempt to jump. According to one study, this is the best way to belay. It would also be interesting to see the effect of the belayer jumping, as is often claimed a dynamic belay.
It would be interesting to compare rope diameters/elasticity and how this affects the forces involved keeping everything else the same. It was very informative to see how the Z line and the static fall created such a high force on the bolt and the climber. I think the video could've have done with a bit more controlling of variables (eg. don't grab rope during fall, keep length of rope same for the basic short/long fall tests) given that Mel and TJ's long and short falls were inconsistent. This was not the most scientific and well controlled test but that wasn't necessarily the aim, either way this definitely provides some great, baseline intuitions about forces involved in taking falls and it's nice to see some numbers :)
I'd love to see breaking strengths and vibration/repeated loading security of different knots (bends & loops especially) in different ropes. Particularly: alpine butterfly (bend/loop), zeppelin (bend/loop), figure-8 (bend/loop), reever (bend), single/double/triple fisherman's (bend), oysterman's knot (stopper), barrel knot (stopper).
Can you do a test with cams, 1:direct to loop 2: biner in webbing, 3 quickdraw 4: unextended alpine 5:extended alpine 6: double length alpine. Falls at 5 m, 10m, 15m, 30m
One of the reasons the bolt force is higher than the sum of the belayer and climber forces due to the system friction. That is, the friction from rope drag through the draws and from sliding through the belay device. Petzl did a similar study and found that forces were higher using a Gri-Gri 2 than a tube-style belay device because there was less rope sliding through the device before lockup. This was also extremely evident in the test you did with the the meandering rope path, where the belayer felt almost nothing, while the climber took a hard fall anyway as the rope bound itself against the quick draws. The other factor is almost certainly the nature of dynamic ropes, which are designed to elongate and absorb energy to reduce system forces. I don't fully understand that effect from a kinetics perspective though. If anyone has a source I can read into, that would be appreciated.
Very interesting video! It'll be nice to measure the forces (on the bolt and on climber) for "factor-ZERO fall" (i.e. top-rope climber fall with accurate belayer and minimal slack), which mimics jumaring foot-slip fall as well. Also, actual numbers of forces (on the bolt) for carefull - vs - not so carefull rappeling from the bolt. Thanks!
There are so many ways I'd be keen to see this done! I'd probably start with varying rope diameters and fall factor though. Although it's less realistic I think the static belayer is better for your test, there's no consistency to a dynamic belay. You could get a rope marker out to be consistent with how much slack the belayer has out too.
Hi, I often climb solo on multi-pitches here in the alps, I'd love to know what forces are generated falling when the other member of your party is simply a belay station! The fact is that sometimes I climb on classic routes which have only pitons, and I'm beginning to wonder how these pitons would react if stressed by a serious fall. However, your are great for what you do!
The sum of the peak forces on the climber and belayer never added up to the peak force on the anchor bolt because of friction on the belayer side of the rope with the wall loops. If both sides of the ropes were free dangling and close to being parallel to one another, then the sum would equal the bolt, as the tension within a given side of the rope would be pretty much uniform along the entire length. And the peak forces at each point would occur simultaneously.
Cam Test would be great! Wedge cement block, rebar enforced mold would be cool to test on. it would also be cool to see Brand shoot out, either Wire gates, screw gates or triple lockers from Mad Rock, Black D, DMM, Edelrid, Camp, Metolius and others...I might even to be willing to donate to this important test.
lqmikey I want to break so much climbing gear. I might beg cam companies to throw me a bone or do a go fund me so I can shit on whatever brands didn’t do well haha
It is normal that the force at the bolt exceeds the two weights combines, because you have to add the kinetic energy of the fall to it. 1/2*m*v2. So the energy added depends on the speed of the fall, and the mass of the climber and the belayer.
The force on the top bolt should be 2x that of the climber minus the force lost through friction on the top bolt. Without any friction you would see the belayer to have the same overall force, however this just snapshots the peak which could still be different. The force on the belayer is that of the climber minus all the friction, even in the rope. On the Z drag you see very little friction and the numbers almost add up. 2.43*2 = 4.86 The friction on the top bolt is4.86 - 4.78 = 0.08 I don't know what's going on with Mel's long and short falls, but he might have held on to the rope and taken some of the force with his arms.
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I would love to have seen more "small falls" - The math of the fall factor favors bigger falls because there's more rope. But what about falls on the first bolt, or falling past the belayer? Factor 1, 1.5, and even 2 (though don't do with with people!)
I'll second this. I'd love to see the numbers as the fall factor approaches 2.
Exactly, great question. Think multi-pitch start from a belay point.
Or hard falling into the first (few) draws, where you try to shorten rope (if Grigri), drop into the rope, make the fall hard for shortest possible distance (danger of grounder).
Also belaying with Grigri
Oh we plan on doing factor 2 falls for sure! It will be fine 🤪
@@HowNOT2 For sure, these are good ideas. Using a Grigri will change things slightly, and keep results more consistent, but the biggest variable that wasn't recorded was the amount of rope in the system. Next time I'd recommend measuring the rope in the system for each fall as you can get a measure of how much the dynamic nature of the rope has an effect on the numbers.
Different belay devices would be really interesting. There's a lot of slip belaying with an atc, but I'd be curious to see a gri, smart, jul, etc.
www.petzl.com/US/en/Sport/Influence-of-the-belay-device?ActivityName=Rock-climbing You are correct. The increase in slip of the tube style device lowers the overall force.
Since most of the belayer were not anchored. They’re force was pretty much their weight. Different belay devices would be more of a factor if they were anchored. Fun experiment either way!
@@tobiaslilja879 Why experiment? Just do it safely.
For large falls the peak forces will depend on the rope more than the belay device, particularly for the top anchor. It is also worth remembering these are relatively small falls with fall factors < 0.5
@@tobiaslilja879something I noticed is the way they were anchored isn't exactly the same as a fixed point belay outside. In real life, the belayer absorbs the force a lot more.
The ropes are durable and just like the ones at the gym. ua-cam.com/users/postUgkxTFxba6lNeHrZaHoY_LXe6ZzmMfaipnwu Caution: I bought the 50 feet ropes and they are long and heavy so make sure you have the space (I do have the space). If I was to do it again I would probably get a shorter version as 50 feet (25 feet each side) is a little long.
Ryan, as a ~330lb climber I would be very glad to see some experiments with somebody my size. My gear fear continues because seeing tests with people that weigh half of what I do doesn't fill me with confidence that I can ever lead climb safely.
Maybe double the force
i actually have a co worker who has started lead climbing at 280 and although we havent done force tests, i believe you can also do it safely, especially if you are not taking huge runout whips or trad climbing
@@devswell6538or lose some weight or pick a different hobby lmfao
F=ma, meaning if you double the mass, you double the force. so if a 150 pound climber generates 2 kn, a 300 lb climber generates 4 kn from the same fall. still plenty low enough for all the gear in a gym.
There is a very well presented grabbing instinct by the falling leader which additionally lowers the reading on his dm because he happens to grab above it. Worth pointing out.
MDClimb true. It is always scary to just fully let go! Haha
@@HowNOT2 maybe for some of us :) I've been letting for for 28 years
Grabbing the rope or gear is a habit that everyone should break. A friend grabbed the rope while falling and lost a finger! But not while I was climbing with him...
For science!!
@@HowNOT2 i think a similar idea is when the belayer is catching they are also pulling with their arms.
Watching this makes me feel so much better climbing outside. It turns out that it's pretty hard to generate an amount of kilonewtons that threatens even basic gear's tolerance. Good to know!
The integrity of the gear is one thing. To place and use it PROPERLY is the MAJOR factor, and there's plenty of ways that can be done so your gear pulls out at far lower loads. In fact, if the belayer is too far back from the rock, simple tension on the rope can lift pro out of well placed positions (particularly a nut placed for a downward pull. I've seen that too many times on the beginning of Double Cross in Joshua Tree just b4 the crux! The lead climber steps up into the crux and the last 2 placements pull b4 they get into the crux! The day I finally had the juevos to lead it we walked up to the base of the climb and there was a huge blood stain on the rock at the base. Bad juju that day. Walked away from the climb.
Hell, the rock can break too! I had a chunk come off on a roof I was really yarning on in Aspen. I came flying off penduluming off the piece I placed and came slamming backing a pointy rock - which luckily hit me right on my chalk bag! I was damn lucky on that one!
For the question why the forces don't add up I was instructed that the friction in the draws and the elasticity of the dynamic rope help absorb part of the energy.
As for suggestions. I've plotted all the data you provided, including climber and belayer weight, and did not find any correlation to the results. I think there are more variables than considerate.
Some things I would do trying to get more consistent data:
1- Have the climber fall when the knot on the harness gets to a reference point, this would mitigate any problems on having more or less rope on the system depending on the climber height.
2- Have the belayer positioned always on the same spot, same justification as above but now considering his position toward the wall.
3- Guarantee that the belayer has a standard slack/no-slack amount of rope on the break. Same as the two above.
4- Measure how much rope is the the system from the break till the climber. Having the estimated fall factor might help understand the trends.
5- Have more than one fall for each test, average or deviate the numbers so there is more consistency to the results.
6- Have tests where the climber is lighter than the belayer. This situation is very common and might look more a static fall
7- Try different setups with less or more draws in between. You can never have too much data lol
8- Rope technical information. We can add the elongation on the math and try to determine the influence on the rope on the system.
I think that with this much information we can try to determine between fall distance or weight difference which contributes more to increase the load, as well as any correlation with the fall factor and how much impact does having more or less draws has the in the system.
I weight 211, and always feared that when I fall I was pushing more KN than that. Is good to know that I can still add more load on the rope before snapping it.
Like I said before, what you are doing here is extremely helpful to the community, if I can help on any way just let me know.
Vitor Viotti thanks! I think it would be nice to get a usable model so you would be able to predict within half a kn what you are generating. We will brush over many unanswered topics in climbing then go back through with a more scientific approach for sure.
@@HowNOT2 Glad I can help. And I wish I could participate in making the fun part with the experiments
@@HowNOT2 You could minimize the friction by only being clipped in to the last bolt. Maybe setup a locking one for the last one and unclip the rest. I say minimize because I'm not sure how the rope drag on the last draw will factor in
All excellent advice. The largest confounding elements are almost certainly the length of rope in the two halves of the system and the friction from the draws.
It would also be interesting to see the net accelerations applied to each side of the system (falling climber, and belayer). F = ma, so should be easy enough to figure out.
Also, the numbers will only add up if all three dynos experience their max load at the same time. This won’t be the case due to the friction and the dynamic rope. The climber’s dyno will experience max force at the moment that his side of the rope is at max extension, the belayer’s will be at the moment (later) when his side of the rope is at max extension (likely the moment he leaves the ground), and the anchor will be somewhere in between.
This was awesome. More please!
As to why they don't add up,
- work done by friction
- difference in catching "softness"
- amount of rope to increase the time in the equation of (Force × distance)/time there by decreasing the amount of dynamic peak loading
Really well made. Could watch this all day. Looking forward to the following ones.
Looking forward to “falling” would have been a funnier response
I wish I could subscribe and thumbs up twice. This is exactly the kind of testing that the climbing community needs. Just knowing that big falls and small falls only produce relatively small fall factors (relative to gear ratings) is so confidence inspiring.
Some comments below talk about ways to improve the scientific aspects of these experiments by isolating various features, adding limiting knots, etc. with worries about energy and momentum conservation. Unless the goal is to create a model that can predict within half or a tenth of a KN, which seems impractical in the field, then experiments like these have the correct approach: test high probability fall scenarios. There are definitely 'classic' routes that are super run out, where higher fall factors can occur, but in most sport and even trad settings, bolts and gear placements are close enough together and in relatively secure places. I would love to see you guys continue this line of inquiry!
It's important to note that this video only tested small fall factors (as defined by UIAA, fall distance vs. rope between climber and belayer), and higher fall factors can occur (and indeed, are more likely to occur) with less rope out, which means that forces can be much greater than measured in this video; less rope between climber and belayer means less stretch distance, which means higher impact force even if the fall distance is the same.
No experience in Climbing, climbed once in highschool when i was a kid, never slacklined, still watching your videos anyway, for the science, and the logistics insight !!
I feel like there aren't any good videos explaining fall factors, and that type of content would suit this channel really well. I bet you could make a video MUCH better than what's out there right now.
YES! we can have fun AND be scientific
Jo69 there are a few videos on falling and types of catch and their effect on the climber by the UA-cam channel “Hard is easy”. (It used to have another, imo better name). It would be nice to see more though.
I weigh 245 lbs, I’d love to see what kind of forces my weight places on the gear! It’d be real cool to see if it’s graphable on scale with weight/height of fall. I also climb with an Edelrid ohm, because most belayers weigh less than me. Have you thought about testing these out to see what kind of load/force reduction they actually make for the belayer?
And since the belayers weigh less than you, you need to anchor them so they don't get pulled through the first draw. Would love to see the forces in that case as it's a worst case scenario. 245# isn't unusual when you have a rack of gear.
@@GodzillaGoesGaga are you carrying a 50 lb rack? lol
The length of the fall isn’t a good measure of severity of fall. Their longest fall was actually one of their least severe. A much better measure is fall factor which is (fall length)/(amount of rope between belayer and climber). fall length is the length in free fall, the distance the climber falls once the gear is weighted doesn’t count. None of these falls was > 0.5 so they are all minor. Their “long fall” actually had a lower fall factor than their typical falls. The “Z” fall was the worst because the rope drag effectively reduces the length of rope in the system. The worst fall in a gym is from bolt 3 onto bolt 2 with a FF of ~0.66 which still doesn’t rate as serious. The gear is designed and tested for a fall factor of 2 i.e. a fall from above the belay to below it with no other gear on a multi-pitch climb. Which is why good trad leaders like to get gear close to stances, preferably before leaving on snow/ice/alpine.
We once dropped a controlled 20kg weight on a brand new petzl helmet
It dented!
The exact same model helmet with 5 year's outside use smashed to pieces in the same test.
It's always worth keeping a thought on how much sunshine your kit has absorbed plastic degrades under uv light over time.
Great video thank you 👍
For the forces to add up you would need 0 friction (or remove all other quickdraws before dropping) , both belayer and climber to pull on the quickdraw in the same direction and the peak force exerted by the climber and belayer to happen at the exact same time.
Not all of those things happen, but its very nice to see the actual numbers rather than the rule of thumb calculations for once.
Great video!
Molo Mono yea. Eliminating variables is what so many experiments do. I love throwing in all sorts of monkey wrenches in it to see the range of what we get in the field in real life.
Need more of this available to the community
I love this video. it really backs up why you'd want to use 3 cams for a trad anchor, coming and finding some ball nuts fail at 3.9 kn. Really loved being able to see all the number side by side
Probably already mentioned by others, and just a basic observation (worth testing): with the rope forming a continuous translation of forces through the top bolt, the force on the bolt at impact should be approaching double the force acting on the climber, much like a pulley block with a doubling action except with greater frictional losses, dampening losses through elongation of rope and also a loss through the dampening reaction of the belayer moving in reaction, so this looks great. You'll soon have more real situation data than the climbing manufacturers! :)
As a tree climber i find these videos interesting. What you guys are doing in these tests as experiments reminds me of lowering sections out of a tree. In tree work, climbing we "never" climb above our tie in point.
The tests you were doing we would refer to as locked off negative rigging. I've cleared a fence when lowering (belaying) a piece and a pulley was being used instead of a natural crotch which has friction.
When the pieces being lowered are to heavy to handle without adding friction we either take wraps on the trunk of the tree, or use a friction device at the base of the tree. When possible we always prefer to let it run to reduce dynamic loads on the tree and ropes.
There are some really cool videos out there of rigging, both just showing and instructional.
Stay safe, and have fun :)
P.S experience ropers are highly valued in tree work, as a climber there are times i have to trust the person on the rigging ropes with my life.
Here are the force distribution ratios, for those who may be interested. (code included)
- 76kg (167slbs) Short:
climber/belayer: 2.6
bolt/climber: 1.7
climber/belayer: 2.5
----
- 76kg (167slbs) Long:
climber/belayer: 2.2
bolt/climber: 2.0
climber/belayer: 2.25
----
- 79kg (175lbs) Short:
climber/belayer: 1.8
bolt/climber: 2.3
climber/belayer: 1.8
----
- 72kg (160lbs) Z drag:
climber/belayer: 6.8
bolt/climber: 2.0
climber/belayer: 6.8
----
- 79kg (175lbs) Long:
climber/belayer: 1.8
bolt/climber: 2.0
climber/belayer: 1.8
----
- 86.1kg (190lbs) Long:
climber/belayer: 3.0
bolt/climber: 1.7
climber/belayer: 3.0
----750750
- 76kg (167slbs) Static:
climber/belayer: 2.3
bolt/climber: 1.7
climber/belayer: 2.3750
----
- 72kg (160lbs) Big:
climber/belayer: 2.2
bolt/climber: 1.4
climber/belayer: 2.2
----750
The estimated 86.1kg (190lbs) Long belayer used for the calculation: 78.116
Code: onlinegdb.com/rka4IRA7L
I've been watching a few of your videos and holy moly this really puts it into perspective. This makes it way more interesting.
Great video, love what y'all are doing!!! I would love to see some tests on factor 2 falls. Very applicable to the climbing community, and I'm sure it would pull in more viewers. Thank you Ryan and team!!!
Thanks for the video guy's. I would have liked to see a slightly larger climber, maybe 200lb's or 90kg. I would have also like to see double ropes put to the test and some trad protection, nuts rather than cams. I really appreciate what you have done so far and keep up the good work.
Looking forward to high fall factors.
Would _really_ love to see force vs. time plots.
why? force vs TIME? Makes no sense at all.Its based on the amount of rope in the equation. Dynamic rope stretches. The more played out, the more it stretches and less fall factor.
This is awesome! Exactly what i needed to see! I did some mathematical simulations in the past to see how this all worked. But was never shure about the actual forces due to friction (especially all quickdraws combined) and rope elasticity due to ciclic loading. It changes over time and after heavy falls, rope needs time to reset.
The equalization and highline anker video's were enlightning as well, though the forces are applied in a swelling manner, instead of an abrupt way. This will most definetly have some effects.
Ideas:
- Film with a thermal camera. (Here in the netherlands we can rent them.) This could visualize the heat very intuetively. (quickdraws, belaydevice and rope!)
Request:
- Using these measurement devices in a climing anker. (i know, the lines are to short for that, but i've seen you being creative before! ;) )
- Dropping a load of a (WAY TO HIGH) location. Perhaps using some old discarded climbingropes to see where they would break. The knots or the anker setup.
Notes:
- If you need any help with calculations, I might be able to help ;)
THANKS!
I'd love to see some tests comparing the forces generated in a fall when belaying directly on the anchor vs belaying over your body at the anchor.
Geert Bakker what do you mean over your body? You mean factor two falls?
@@HowNOT2 It's a literal translation from dutch climbing literature but he's talking about the differences between belaying from the anchor, or belaying from your own harness with a quickdraw in the anchor to redirect the rope.
The 2 common types of multi-pitching belaying.
There are tests on youtube that did just that but in a very very misleading way. :-(
@@HowNOT2 ua-cam.com/video/1CbFpRPYDm0/v-deo.html This video explains it pretty well, it's very common in Europe
thanks for testing, i think is the best way to trust in the gear, keep it up!
Climbers weight in "lbls", forces in "Kn" that are direct translated to kilograms... Please help the rest of the world.
Your climbing gear is rated for KN, kilonewtons are how forces are measured, LBF is such a misleading way of measuring forces since the same weight can generate all sorts of numbers. I want to compare KN with the gear so we can make good decisions based on the gear we have. Its 224.804lbs per 1KN btw
@@HowNOT2 I think he was referring to using kilograms for when weighing the people cause the rest of the works besides ghana (IIRC) uses kilograms to measure weight.
As a scientist, *face palm* I mean ffs, even the British who made the imperial system isn't using it anymore
As an American doe, AMERICA. F$@# YEAH!
@@eugenejkim even the U.S. use kg and also the metrical system in physics, because it is international standard.
@@marcushausch except when it comes to multi billion dollar science projects we send to Mars... then we mix up the units and waste billions of tax payer dollars.
It’s kN and kg, k is the only SI-prefix which is greater than 1 and lower case.
Very good video.
1.- Answering the question about why the addition of belayer and climber forces don't equal the bolt. Lot of energy is released stretching the rope and heating the friction points.
2.- It would be nice to see another video stopping falls with a static device like petzl grigri, I presume forces would be quite higher at all points. That's a very popular device in sport climbing that may, or may not, be used in other contexts.
I would like to see a video for solo rope techniques, such as anchoring off the first bolt.
Load testing or just lead rope solo videos technique?
The first slack line I ever walk on was at pipeworks!!! I miss this place so much.
Some work is done on the rope to stretch the rope itself, so the rope essentially distributes the forces throughout. There is still conservation of energy but some of it is lost between the measuring devices to the rope itself, which is why the belay/climber readings dont sum to the bolt.
1. Please try to register full graph from enforcer, not just peak force
2. For us European, refer mass in kg as well (I’m glad you’re into kN :) )
3. Tests I would like to see: same FF, different fall distance (again, full graph); pendulum vs vertical fall of the same fall height; short fall distance, freshly tightened knot vs after multiple falls; static mass vs climber.
4. Thanks for great video!
You should add a dynamometers to each quickdraw. Them are acting like little belayers. That is why you miss some forces at the belayer but more or less you have 2*climber at the bolt. Interesting to note that from 1.5 to 7 (in the Z) times of the climber force is absorbed by the quickdraws.
smaller cams are supposed to hold 5kN so it would be cool to see some experiments on rock on how much they actually hold
New to the channel, really like it! The figure of 8 tightening must be a factor in the load measured, meaning the second fall will have a larger load due to less load reduction, J Marc Beverly wrote a good paper describing this effect
Something I'd like to see when you're next doing this: clip a sling into the load cell and see how much force you can generate by bouncing on it. I've seen it suggested that when learning to place trad gear you test your placements by bouncing on them; it would be interesting to see if that generates forces comparable to a fall.
That's a good idea!
I've climbed a few big walls and bounce test the gear. Instead of using a sling, you should use aiders. This should be harsh since aiders don't have much material to absorb forces.
An interesting thing that happens when bounce testing is some placements that you think will barely hold end up surviving vigorous bounce testing. Of course, placements that look bad are bad,
The biggest benefit of bounce testing while doing aid for me is it improves my confidence in placements when I'm free climbing. It provides real experience in judging placements.
@@WyomingMtnMan My hardest aid was ancient history - pre-cams. It taught me loads about placements, but bounce-testing done correctly only loads slightly above body weight, what a very short, soft fall would impart; this is useless in regard to what forces solid protection and anchor pieces must hold.
The theory is if the next piece fails under its bounce, the previous one has already proven (barely) sufficient to catch you; once a good bounce is held, you move gingerly and repeat the process. A series of marginal placements provide at least the illusion of confidence, in this principle, but the most common mistake is never totally transferring 100% of their weight to the tested placement; any residual weight on the foot in the etrier clipped to the lower piece reduces the force on the tested one, and if you then commit and begin to move up, that extra few pounds may reveal the piece wasn't good enough, after all. By then, your two or three feet of vertical adds a tiny extra force if it pops and you fall onto the previous one, perhaps exceeding what it held in its bounce test - from there, you may enjoy the legendary "zipper" fall, which is perfectly named. Just hope no ledges come to play before something eventually catches you!
This is great. More things like this! Maybe talk about the forces with different belay devices?
I'd certainly be interested to see grigri vs ATC
The forces measured here are almost certainly going to be fairly similar, with the possible exception of minor differences at the belayer's end.
Why is belayer KN + climber KN < bolt KN?
Belayer and climber both enjoy the benefit of rope stretch and friction while the bolt does not.
Note that in general, twice the force at the climber is close to the force at the bolt
Mel's Long fall climber force 1.78 x 2 = 3.56; force at bolt 3.54, a difference of 0.02KN, greater on climber side
Mel' Small fall climber 1.26 x 2 = 2.52; bolt 2.88, difference 0.36, smaller on climber side
TJ small climber 2.14 x 2 = 4.28; bolt 3.72, difference 0.56, greater on climber side
TJ long 1.73 x 2 = 3.46; bolt 3.46, difference 0.0
TJ static 2.65 x 2 = 5.30; bolt 4.52, difference 0.78, greater on climber side
Mel + vest 2.34 x 2 = 4.68; bolt 4.06, difference 0.62, greater on climber side
Ryan Z drag 2.43 x 2 = 4.86, bolt 4.78, difference 0.08, greater on climber side
Ryan K big 1.87 x 2 = 3.74; bolt 2.6, difference 1.14, greater on climber side
Great video. I second one of the suggestions listed below: it would be good to test the Ohm.
One big issue with this test (aside from the lack of measurements of fall height, rope length, etc.) is the placement of the dynomometers on the climber and belayer. If you watch at 6:17, you can see the climber grabbing the knot above the dynomometer, which cancels out some of the force in the rope. The belayer also does this when pulling the free end of the rope to add friction. Most of the results from climber and belayer add up to around 700 to 900 N short of the force felt at the bolt. This is about ~190 lbs. That 190 lbs is easily explained by the users pulling above the meter. This could be improved by placing the dynomometer 5 ft or so away from the user.
The method of measuring done in this video shows how much force is on the harness attachment point, which is slightly less than the force on the rope because of the user pulling on the knot. This could be useful, but you might aswell find the force in the rope as I suggested above in order to find a worst case scenario if the user does not use his hands at all.
Could you test different knots for tying and their relative breaking strength/slippage under load? Considering different dynamic rope breaks at different forces, comparing them relative to reach other on the same single rope would be sensible.
Was thinking of comparing:
Rethreaded fig 8
Rethreaded fig 8 + barrel knot stopper
Rethreaded fig 8 + Yosemite stopper
Single bowline
Single bowline + barrel knot stopper
Single bowline + Yosemite finish
Single bowline + Yosemite finish + barrel knot stopper
Rethreaded bowline
Rethreaded bowline + barrel knot stopper
All when loaded normally (as when taking a fall) and again when loaded 90 degrees off the normal orientation of load (as when you're clipped into an anchor and catching a fall whilst belaying off that rope's loop).
Love the videos and thanks!
Rope access people have a general rule that any knot gives 50% reduction in rope strength. There are so many variables included that it's almost impossible to give consistent results otherwise and they are generally fairly close. If you go for 50% you won't go wrong.
very very interesting!! congratulations to this channel
Do one showing the strength of guide ATCs? I cant seem to find ratings on them however they are made to be clipped in directly and take the same force the carabiners would normally take it seems? But they don't how a rating on them.
In my previous post I stated that the bolt force would always be twice the climber's (faller's) force.
However, this is only accurate under ideal conditions:
1. The climber's and belayer's ropes are parallel to each other. (both pulling in the same direction).
2. The climber is falling directly below the bolt/pulley.
The reasons your bolt forces did not follow this formula (bolt force) = 2 X (climber force) was often due to the quick draws adding friction and creating angles between the ropes. Also the line of fall was often not directly below the bolt/pulley.
This new formula allows for the variable of rope angles to be considered.
Pulley/bolt force = 2 X (climber force) X cos(angle/2)
I did the calculation and found it to be a fair match with the data you provided.
In my calculation I used rough estimates of the angles I observed between the ropes during the max pull of the fall, which changed from one event to the next.
In the Ryan Big fall, the angle between the ropes was far greater than all the other events. And the fall path even more out of line with directly below the bolt (causing a lot of swing). Swinging into a lower elevation has much lower accelerations than falling straight down until you hit the end of the rope.
Summary:
The odd rope angles and frictions in the system tend to redirect and distribute the forces (created by the falling climber) away from the bolt, and into other parts of the rock (attachment points of the quick draws).
What the experiments do demonstrate is that the forces on the ropes and bolts are complicated to calculate and affected by a host of variables (I noticed at least 10 contributing variables). We also have shown with data and calculations that:
1. The pull on the bolt will never exceed twice the pull on the falling climber.
2. The pull on the belayer will max out at a force equal to the force on the falling climber.
3. Increasing friction increases the forces on the bolt and climber, but reduces the force on the belayer.
4. Increasing the angle of the climber's rope relative to the belayer's rope reduces the force on the bolt.
5. Falling from a point not directly below the bolt results in less force on the system (bolt and climber)
FYI: in Mel's small fall the bolt force is more than double the climber force. I believe this was a result of Mel grabbing the rope above the force meter, so the meter did not read all the force on the falling climber. (this may have happened during other falls as well).
Dan Gillam I’m afraid your analyzing it as a static’s problem when this is a dynamic problem. this idea that the net force should come to zero is only true for non-accelerating systems. Since the faller has to come to a stop, there has to be a net force in the upwards direction to create that acceleration in the upwards direction, and the extra force from the bolt is providing that extra force in the upwards direction. This is described by Newton’s second law
Bolt peak force would only be double the force on the climber if there was 0 friction at the bolt. If, for example, friction was near 100%, you would have the same force on climber and bolt. Even if the angle is 180 at the bolt. (Maybe that’s what you are saying and I misunderstood, sorry if so!) 😀
@@adamlightman8953 The rope pulls up on the climber, and the climber pulls down on the rope. If there were no rope in between them then these forces would always be the same. (this assume no pulley, just a climber tied into a bolt. Even with a stretchy rope the force down on the bolt end of the rope will nearly equal the force up on the climber end. There is a net force on both end objects. The climber is accelerated upward, and the bolt/Earth is accelerated downward. In the video there are a lot of other things pulling on the rope, so the situation is more complex. Also there is a delay caused by the stretch rope (the pull down at the top does not happen at the exact same moment as the pull up on the climber, consider the pull to travel through the rope as a compression/longitudinal wave). The impulse at top and bottom would be the same (impulse = force X time), but it is possible that the force at the top was lower magnitude for a longer time, and the force at the bottom was higher magnitude for a shorter time. Newtons laws apply to all situations, dynamic and static.
@@johnliungman1333 That is true. In a situation where the climber is tied to the bolt (100% friction), and there are no other attachment points. When you introduce a pulley into the system you also introduce a bunch of other attachment points, and the downward force ends up being distributed and redirected. Theoretically if you could measure all the downward pulls (impulses) on the wall, and all the upward pulls on the rope ends they would sum to zero. Having a pull on the other end of the rope also tends to make the climber's pull go to the side, so that the force meter is not in line directly between the climber and the bolt. Then it would take a vector force analysis to determine the component of the climber rope force that was acting inline with the force meters (which is what the meter measures).
Some suggestions:
I would love to see a comparison of different Fall factor Falls. Lets say a fall after the first bolt and a big whipper from the top.
Also could you test a massive multipitch lead fall where the climber falls below the belay?
DIfferent Falls on different belay devices would be great also to check out the difference for a grigri belay vs. atc in trad.
Keep up the nice content!
I'm in love with this climbing gym. So jealous.
Excallent video. The answer to your question is that there are forces generated by the fall and the catch that cannot be absorbed by the system (belayer+belay device+rope).
The only instance where the exerted force is lower is when you have a long stretch of rope that can absorb the force of the fall. In the big fall the forces of the climber and the belayer add to 2.71 kn and the bolt reads at 2,60 (-0,11)
The more static the fall the higher the reading for the bolt is (z- drag and static fall)
I see that you belay with an atc, which makes a pretty soft catch. Could you do the same tests with a gri-gri? I think the forces generated by the autolocking devide will be higher on the bolts.
Thank you very much for this very interesting video; I´d like to point out that most tests are done by throwing down a weight that doesn´t resemble at all the way a person falls and tend to give results that can hardly be extrapolated to real climbing, yours on the other side does it as it should be done. Thanks again
Rad research guys! Outside I’d love to see some lead rope solo (static belay) tests because I do that a bit and it has the highest loads.
Oh, we are going to do some big ones! :)
Having a dynamic belayer helps reduce the force by adding "virtual" stretch to the rope, and more time to decelerate the climber. In a high friction pulley (carabiner), the climber's force would approach the force created by a rope tied to the bolt. However the force would still be less due to the slip of the rope around an pulley in an anchored belayer system.
This makes me feel so much better as a rope tech that my gear is designed to take over 8x times the shock loading of the hardest fall here. The force required to actually break my gear is equivalent to forces that would literally shatter all of the bones in my body lol.
The space between bolts in some routes here in EU is sometimes 5+ meters (16 ft). Would love to see a 10+ meter (33 ft) whipper.
Places were energy is being lost and not meassured, explaining the difference.
- Rope drags on the quick draw would heat it up, which would not be meassured.
- The rest of the quickdraws on the route, which where not meassured.
- Rope absorbs some of the energy of the fall, by streching.
If belay device was grigri, I think force on belayer's dynamometer would be higher (because belayer's hand takes more force with ATC), also friction on quickdraws reduces force on the main bolt. It will be interesting to test other fall factors as well as top rope.
Can you elaborate on that?
Grigri vs atc can probably have some affect on it.
The bolt force was MORE than the climber + belayer, not less.
Friction on quickdraws does reduce the force on the top bolt (pulley), while more friction on the top increases the force on the top. You could further reduce the force on the climber by using a low friction pulley at the top, but you better tie down the belayer so he does not get pulled all the way up the mountain. The more slip (less friction) in the system (belayer or climber) the less the forces will be. More friction means more force on the ends of the rope (climber).
@@HowNOT2 the way how it is belayed has definitely a huge effect on forces... www.petzl.com/US/en/Sport/Influence-of-the-belay-device?ActivityName=Rock-climbing
Hey Ryan, we'd love to see more tests with climbing gear here are some ideas from my end:
- Edelrid MegaJul how much is needed to break this device? it look weak (and is cheap in testing because it not expensive)
- Quickdraws: my (online)research showed that most of them are barely over the mbs
- Friction until burn is this possible? e.g. a 100m rope with e.g. 100kg and high friction on the belay device (e.g. tube) use 99m and stay on the last meter, is it so hot that it burns trough?
- zig-zag belaying in case the belayer weight is much less than the climbers weight: what could go wrong?
The rope NEVER passes directly thru a runner. The rope only goes through the binder and belay device, so the runner is never involved with any friction or heat. Your belay device may get very hot on a long rappel, but any portion of the rope is only in contact with it as it passes thru on your way down.
I'd like to see a test of a leader fall that zippers out a few questionable pieces of protection. do the first couple of pieces take enough of the force to allow the 3rd piece to hold the fall? Also, how good does an Ice screw placement need to be to catch a screamer?
Why do people ask such ridiculous questions? You want them to purposefully place gear to fail andthenjump on it for your entertainment? And why would you ever even think of testing an ice screw if it's questionable at all? You do realize that cli.bing isn't a game dont you?
Would love to see same tests done with DMM revolver.
There was a big math argument years ago among mechanical engineers and I’ve wanted do this test forever.
The question being, using a revolver would lower or raise the force seen on an ice screw or crappy trad Cam placement?
It looks pretty clear though that:
Higher friction in the rope *after* the top carabiner = higher force.
What about @ the carabiner?
Seriously. I’ll doordash beer to Sacramento for you guys doing the test. (With enough notice I might even drive up and bring the beer myself!)
HMU.
This is what I want to know as well. You have arborists designing devices to add friction at the top and reduce mechanical advantage and climbers reducing friction at the top in an attempt to reduce fall factor! Which is it? Or is there just any appropriate amount of friction..
www.portal.treebuzz.com/where-should-friction-be-in-our-rope-rigging-systems-672
Agree that adding revolvers on anything before the top piece should free up more stretch lower in the system and lower the fall factor
sorry if i'm bombarding your post! but i'm thinking this through further as i am doing the washing up. i have a thought that small falls with heavy weight might benefit from more friction but at a point there is an inversion and the light weight big fall brings the fall factor into focus. i imagined arborists and climbers both looking at a spoon from different sides(!! :) )and seeing a reflection right side up and upside down with the focal point just to one side. No i'm not smoking anything. I would guess a small slump onto a microwire might fit my first catergory. No maths to back this up, hope someone can put us straight.
Neil D
My thinking is that the peak force always gets clipped as the weight of the belayer comes off the ground. (Which is where all the math I’ve seen missed. They assume belayer is infinitely heavy.)
So in a zero friction system the peak force is only limited by the amount of time it takes to accelerate the belayer (which should be some time constant based off the stretch of the rope/fall factor/meat squishy ness/harness, etc.
In any ice climbing/micro trad piece where the fall must hold the weight of the climber, I’d rather it lowered the peak force on the piece.
Great channel and educational stuff you guys have is over the moon !
Cant wait for trad gear testing to come!!!
tin cvitkovic awesome. We are going to destroy trad gear. Just made an adapter for my Slacksnap machine! The ClimbCrusher haha
Very interesting - thanks. There are lots of tricks used to reduce shock loads on trad gear: use of half ropes rather than singles, "soft" catches, revolvers / screamers on marginal gear, equalising pieces or clipping them to different ropes etc. It would be great to see some data on whether these actually work
And, as others have said, can you give climbers' weights in kg please? It's much easier to work out accelerations in a consistent set of units
I think the total force on the top bolt is the sum of belayer force, climber force, AND drag on all the bolts below which is where I think the missing force is going. (hands off the rope during the fall would possibly help generate cleaner data.)
Dux Bellorum we will be sure to let go next time 😂. The variables is what makes real life testing so much fun
@@HowNOT2 I'm an applied math PhD student and between you guys and some video analysis and models put up by "Hard is Easy" I'm starting to get curious about further mathematical modeling of lead fall dynamics. More data more better =D
One other thing you could do is put a fixed camera across the room perpendicular to the plain containing the climber start position - end position - and top quickdraw, to record the falls. Would enable video-analysis to find position of the climber at each time, i.e. their acceleration and trajectory. Bonus points for having a meter-stick in the same plane to help scale the distance.
The reason Bolt does NOT equal climber + belayer.
The belayer and the climber both pull down on the bolt/pulley with their indicated forces.
However friction with the "pulley" causes the pulley to pull up on the rope (and thus the rope to pull down on the pulley, Newton's 3rd law of motion).
It is the frictional force that causes the discrepancy between the force on the belayer and climber. The amount of the friction must therefore be equal to the difference between the pull on one end of the rope and the other (discrepancy).
The total down force on the rope is equal to the sum of the climber and belayer, plus the pull created by friction.
Climber force minus belayer force = friction
Friction + climber+belayer = total downward force on pulley.
Here is one example from your data.
(1.78 - .99 = .79 friction)
climber + belayer + friction = total
.79 + 1.78 + .99 = 3.56 theoretical total (actual measure total was 3.54)
FYI: you can also get the calculated total simply by doubling the climber's fall force.
1.78 * 2 = 3.56
FYI: using a low friction pulley would decrease the difference between the belayer and climber, but the formula would still work. In the absence of friction the belayer and climber would be equal, and their sum would equal the bolt. However, you would never be able to have a 100% efficient pulley due to the internal friction of the fibers as the rope stretches and bends.
FYI: I am a high school physics teacher, and hobby climber (top rope and TRS only).
dynamometer on each bolt will give a closer sum of forces. Since all the bolts help to distribute the weight of the climber and belayer then the entire system needs to be included in the free body diagram. It is true that the top and bottom bolts will see the most forces; however, two test points only allow for assumptions to be made and not create an entire sum of forces.
Long & short falls: in spite of the length of fall, more dynamic rope to extend the period of application in the long fall and constrain the forces on the bolt and belayer so not major differences in the pattern of forces.
Static fall: pushed the numbers up by introducing rgidity into the system.
Z Drag: made the friction do the work to protect the belayer but in doing so prevented the entire length of dynamic rope coming into action which would otherwise have reduced the force on the climber and the bolt.
Big fall: the force on the bolt is reduced because the climber and the belayer are not applying forces to the bolt in the same direction because the fall is at right angles to the line of the rope. (Thought experiment: if he had left the roof and started climbing down the other side then a bolt placed there would have seen almost zero load.)
Yes I love this, more climbing related content please :) I think friction is the reason the forces don't add up perfectly.
I haven't seen much on the physics behind the measurement, so here's a try.
First of all we see, that the climber falls into the rope, that attached to the anchor. On the other end of the rope there are some quickdraws and the belayer.
So
belayer + friction in quickdraws = force on climber.
This explains most of the results: the force on the anchor is approximately double the force on the climber in all cases, because the anchor holds both ends of the rope.
The belayer doesn't experience the full force because the quickdraws on his end absorb some force due to friction.
Last but not least we must explain the minor differences in comparison to this theory:
As mentioned in the video, only the maximum force is measured by every dynometer. But what really had to be absorbed is the energy of the falling climber. Physics tells us E=F*s (Energy equals force times distance) (Precisely this is an integral, which leads to nontrivial mathematics)
So if the climber has less rope stretch on his end, his energy is absorbed over less distance than the belayer uses to absorb the energy, resulting in yet a lower maximal force on the belayer's end of the rope. Thus the force is more equally divided and we measure a less high peak force.
I'd like to see this same experiment with the Elderid Ohm incorporated with its own meter to see how much force it really does eliminate from the rest of the setup.
I just have to ask "why"? It won't make any difference in how or what you climb. IF YOU INIW WHAT YOUR DOING, any device, and even no device ( hip belay) will catch a fall. They've been doing it for decades.
I appreciate you making these videos. Learning a lot! Thank you!!!
Awesome video! I was wondering just the other day the forces on climbing gear. Good job!
I'd love to see a dynamometer on a cam(of different sizes) catch a whip outside (backed up with a bolt below) and see what kind of forces it has. Curious if they're less or more than the bolts in a gym.
Colin Woodside Just think about it, If you fall from the same height with the same rope and slack it doesn’t matter at all how you are connected to the wall, the only difference will be, that the cam might pop out, the force is still the same.
Awesome stuff, thank you!
The force of the fall is also being distributed along all of the hangers you clip into as the rope drags through the carabineers therefore decreasing the amount of force the belayer is experiences
You teased us with "you'd be shocked with how little it takes to break a dynamic rope". In another video I think you had a rope from the 90's break at around 12kn, maybe? I was wondering if you could do some climbing ropes with different amounts of slack in them, as the weight is distributed along the rope in the event of a fall.
To describe the difference in forces at the bolts, relative to the sum of the forces at the belayer and climber, you must think in terms of inertia or energy. Both would give the same result, but would paint slightly different pictures. The bolt absorbs the energy that the rope cannot. Or in terms of inertia, the total force is equal to the changes in momentum of the climber and belayer, divided by the time of the interaction. Inertia and impulses are (in my opinion) the best ways to carry out a dynamic analysis of most climbing falls. But sometimes energy principles are slightly more simplistic.
Great science! Thanks for your videos and experiments
I’d like to see the worst case and best case. Worst case is probably a heavy climber’s factor 2 fall from above a belay station when belaying from the anchor with an assisted braking belay device. Small nuts are only rated for 4kN, would be interesting to try it on them. Best case is probably a top rope fall or a follower fall on a multi pitch route. Would also be very interesting to see how much softer the fall is with a half rope (and how much harder the fall is with two half ropes).
Most people are concluding how hard it is to generate a large force, focusing on the people (belayer and climber). I’m a trad climber and expect/require my belayer to be anchored on multi pitch routes, that test did increase force by reducing the dynamic absorption/offset occurring when belayer is pulled upwards. My focus then goes to the piece of gear catching the fall. Seems 5-6 Kn is going to be common. Some gear is not much more than this AND some placements are definitely a lot less than this. How and what gear you place therefore becomes the most important factor (if that isn’t overstating what should have been obvious to all of us, even before this test).
I’d like to see more on forces on trad gear in different types of placements. Maybe on a Big Wall 😀
Brilliant. I've been looking for a video like this, and this is exactly what I wanted. Thanks a lot!
Robert Stefanic thanks.
Brilliant video! I’d love to see how a pulley carabiner helps with force at the bolt. Also how a fresh rope compares with a “tired” rope (one fallen on multiple times)
We did test an old rope but didn't include it in video because it didn't really change anything and too much data in one video dilutes what we had. We will specifically test this later after we trash a dynamic rope and make it lose most of it's dynamic properties.
@@HowNOT2 It wasn't old rope but new rope that had been fallen on a few times rather than new rope that was fresh... Nice to know that older rope is still bouncy though :-)
I would expect the pulley to increase the force on the bolt. Like a pulley 2-1 can pull more than non pulley
@@neild7971 if it goes round something it's a pulley. A more efficient pulley will reduce the load on the climber and increase the force on the belayer. The force on the gear (quickdraw, nuts, etc) will be reduced also as the fall factor is reduced
@@largeformatlandscape are you sure the force on the gear is reduced with a higher efficiency pulley. any info would be appreciated as this interests me.
Great experiments. About the adding up problem, I would say friction not transmitting all tension to the belayer. Easy to test with some oil.
Thanks for the information I will send you some stuff when I finally start my gym. Got some crazy ideas
Sounds good. We are getting way better dynos soon to do more testing like this.
Would be cool to see the forces when hauling on the bolts/anchor and hauler with multiple bags and portaledges. Also the working load forces on the pulley's with a mechanical advantage systems of 2:1 and 3:1.
The peak force on climber + belayer does not add up to force on a bolt, because dynamic rope makes the force more spread in time. If you would calculate integral (sum over the whole fall) you would get the same value. Basically, due to elasticity of the rope climber decelerates faster than belayer accelerates.
I think the bolt experienced more force because it is solid and can’t/won’t move when the fall happens, thus there is no force absorbed as there is for the belayer and climber due to stretch of equipment and the non-static nature of their anchoring.
Thank you fo for this video. This made me feel a lot more safe and confident in the equipment that i use. Especialy in the carabiners.
Great video, informative and really useful. I'd very much like to see some results for heavier climbers (220-250 pounds for example) and to see the results of Mike 2.0 taking the first fall but with a fixed belayer and him taking the larger fall from the top of the gym. Finally (and this would require a bit more ropework to safely set up, it would be very interesting to see the results of taking the same length of fall onto a shorter length of rope by having the belayer belay from a hanging on the 2nd bolt (and off to the side for safety) and the leader take falls from the 4th bolt as they did in this video and ending up hanging well below the belayer.
Your simulations are great for showing how forces develop in a normal day-to-day climbing fall but there are many times when climbing, particularly outside, that you have to push the boat out a little bit, run out further, rely on gear that is well below you or climb as a heavier climber complete with 10 pounds or more of kit with you (consider ice climbing kit as an example). It would be useful to see what happens to those fall forces when you push the envelope a little bit.
I'd like to see the force on the climber with a static fall, where the belayer can move up to 2 feet before the belayer's anchor takes up tension. The belayer does NOT attempt to jump. According to one study, this is the best way to belay.
It would also be interesting to see the effect of the belayer jumping, as is often claimed a dynamic belay.
It would be interesting to compare rope diameters/elasticity and how this affects the forces involved keeping everything else the same. It was very informative to see how the Z line and the static fall created such a high force on the bolt and the climber.
I think the video could've have done with a bit more controlling of variables (eg. don't grab rope during fall, keep length of rope same for the basic short/long fall tests) given that Mel and TJ's long and short falls were inconsistent. This was not the most scientific and well controlled test but that wasn't necessarily the aim, either way this definitely provides some great, baseline intuitions about forces involved in taking falls and it's nice to see some numbers :)
I'd love to see breaking strengths and vibration/repeated loading security of different knots (bends & loops especially) in different ropes. Particularly: alpine butterfly (bend/loop), zeppelin (bend/loop), figure-8 (bend/loop), reever (bend), single/double/triple fisherman's (bend), oysterman's knot (stopper), barrel knot (stopper).
Can you do a test with cams, 1:direct to loop 2: biner in webbing, 3 quickdraw 4: unextended alpine 5:extended alpine 6: double length alpine. Falls at 5 m, 10m, 15m, 30m
the belayer is positioned in a way that creates rope drag and modifies the fall factor.
One of the reasons the bolt force is higher than the sum of the belayer and climber forces due to the system friction. That is, the friction from rope drag through the draws and from sliding through the belay device. Petzl did a similar study and found that forces were higher using a Gri-Gri 2 than a tube-style belay device because there was less rope sliding through the device before lockup. This was also extremely evident in the test you did with the the meandering rope path, where the belayer felt almost nothing, while the climber took a hard fall anyway as the rope bound itself against the quick draws.
The other factor is almost certainly the nature of dynamic ropes, which are designed to elongate and absorb energy to reduce system forces. I don't fully understand that effect from a kinetics perspective though. If anyone has a source I can read into, that would be appreciated.
Very interesting video! It'll be nice to measure the forces (on the bolt and on climber) for "factor-ZERO fall" (i.e. top-rope climber fall with accurate belayer and minimal slack), which mimics jumaring foot-slip fall as well. Also, actual numbers of forces (on the bolt) for carefull - vs - not so carefull rappeling from the bolt. Thanks!
Top ropes are definitely next! And maybe simul rappelling because that has always scared me! haha
Great fun watching your video. It would have been interesting to try to capture how the much subsequent falls on the rope increased the impact
There are so many ways I'd be keen to see this done! I'd probably start with varying rope diameters and fall factor though. Although it's less realistic I think the static belayer is better for your test, there's no consistency to a dynamic belay. You could get a rope marker out to be consistent with how much slack the belayer has out too.
Do all of you want to play with the ropes and equipment they'll ruin with all these keen tests?
Hi, I often climb solo on multi-pitches here in the alps, I'd love to know what forces are generated falling when the other member of your party is simply a belay station! The fact is that sometimes I climb on classic routes which have only pitons, and I'm beginning to wonder how these pitons would react if stressed by a serious fall. However, your are great for what you do!
The sum of the peak forces on the climber and belayer never added up to the peak force on the anchor bolt because of friction on the belayer side of the rope with the wall loops. If both sides of the ropes were free dangling and close to being parallel to one another, then the sum would equal the bolt, as the tension within a given side of the rope would be pretty much uniform along the entire length. And the peak forces at each point would occur simultaneously.
any chance you'll do the same experiment on trad gear?
Cam Test would be great! Wedge cement block, rebar enforced mold would be cool to test on. it would also be cool to see Brand shoot out, either Wire gates, screw gates or triple lockers from Mad Rock, Black D, DMM, Edelrid, Camp, Metolius and others...I might even to be willing to donate to this important test.
lqmikey I want to break so much climbing gear. I might beg cam companies to throw me a bone or do a go fund me so I can shit on whatever brands didn’t do well haha
It is normal that the force at the bolt exceeds the two weights combines, because you have to add the kinetic energy of the fall to it. 1/2*m*v2. So the energy added depends on the speed of the fall, and the mass of the climber and the belayer.
Force and energy are different quantities. You can't simply add them.
Let's goooo! This is my home town bro!!! I got to granet arch tho! Pipeworks kinda to expensi,expensive,
The force on the top bolt should be 2x that of the climber minus the force lost through friction on the top bolt. Without any friction you would see the belayer to have the same overall force, however this just snapshots the peak which could still be different. The force on the belayer is that of the climber minus all the friction, even in the rope.
On the Z drag you see very little friction and the numbers almost add up.
2.43*2 = 4.86
The friction on the top bolt is4.86 - 4.78 = 0.08
I don't know what's going on with Mel's long and short falls, but he might have held on to the rope and taken some of the force with his arms.