There's a LOT of research & development going on in the CVT, digital drive, combined motor+gearbox, and hydraulic drive spaces! What bicycle drivetrain tech would you like me to cover next? 🎉
I love your videos on non traditional gear. I share your passion for belt drive bikes. But this tech I feel is not going anywhere. No disc brake + not good for e-bikes tells me that.
@@pumpkinjutsu1249 "Continuously Variable Transmission: A continuously variable transmission is an automated transmission that can change through a continuous range of gear ratios. This contrasts with other transmissions that provide a limited number of gear ratios in fixed steps."
I've had a Stringbike a few years ago. It was really finicky to adjust, and those D-shaped things could bend really easily during transport, the complete system seemed to be very complicated and sensitive. Pedaling on it was not bad though, but I think the conception created more problems instead of solving them. Btw the website went down a few months ago, I think they don't exist anymore...
Thanks for the insight regarding the lever arms, and adjustment! I actually used one for a while in 2012, although that was not long enough to find any issues. I thought it felt nice to ride once I'd adjusted to the elliptical driving path.
Yes, they went bankrupt a few years ago. The bike industry pushed them out and the selling number was low. I never tried, but theoretically, it brought a better (and, yes unusual) pedaling result. So, it's funny. The video is about an already fallen concept and excited about it.
Love the out of the box thinking with the string bike. Dyneema is used as an alternative to stays and shrouds on a sailboat to keep masts up, so that hints at how strong this line is.
The other limiting factor for the technology was the company who owns the patent for it. One of my relatives wanted to do business with them as the drivetrain would have been ideal for the particular use case (not a bike). He said they were not flexible in improving or adopting the idea, they created terrible quality of products and in general, were really hard to work with. So they ditched the idea and stayed with a regular chain drivetrain.
Oh well maybe it will be useful whenever the patents run out if it is even remotely relevant at that point and somebody finds out/remember that it was a thing
@@oneofthesixbillion yeah but then no one in their right mind would ever invent anything. It takes years of effort,countless failed attempts to come up with something that works, and then works efficiently, and then works at cost. Then you have a bozo that comes after and copies it. We would have no innovation and people who would invent would never share it to a public avenue in that case. The opposite would happen
To increase competition all patents should be on an open licence, as long as something like 10% of the product price is paid as royalty fees there is no violation.
I love the way you analyze, examine, think through, organize your presentation, state your case...everything. I have been looking for an exposé on string drives for a couple of years, and this covers everything I wanted to know. Thanks, and all the best.
I owned one of these, bought it second hand. The gear cables are a pig to fit and need special gear wires at the cranks which took forever to get from Hungary (I'm in the UK). The shifter uses two standard gear cables wrapped around a cylinder inside the shifter. Then there was the issue of balancing the gears on the cranks so gears changed in synch on each side. Effectively there were six cable ends to secure and balance at the bottom bracket: two cables coming from the shifter and the two ends of the two special gear wires, one on each crank. I sold it to a friend and he still rides it but getting replacement cords and other spares is a real problem.
modern belts can last upwards to 30k km.... well certainly not the Gates CDN, mine gave up under 2k km and after that i researched and many had the same issue. turns out Gates be like "yeah that ones not for actual use. only on tarmac with no gradient and no dirt and if you dont drive much and dont go fast." what a piece of junk. always get the CDX if you want a real belt.
i have a clssical mountain bike with chain drive, which i have been using for 25 years, never changed the chain. actually never even oiled the damn thing. so 1000 km to 2000km range of duration for the strings seemed a litle bit short to me.
I think it’s really cool, if only for the mechanical novelty aspect of it. The fact that it worked as well as it did, is testament to the team’s knowledge and hard work. Unfortunately, for it to work for the masses, it needs to be much easier to work with, cheaper, and have wider compatibility. Great video once again. Cheers from Australia
yeah string drives have their advantages I like having the choice of which ever one I want to use on a bike chain or string drive cause choice plain and simple
It's kind of like that Kick 'n' Go scooter that had a pedal behind you you could pump to get going, but it only had a little success for about 2 or 3 years and the concept dropped. Nobody else took it up and ran with it. It didn;t really sell more scooters.
I find it so interesting that every one of these videos about different drivetrains always come to the same conclusion : belt drives are sometimes the best option, chains are almost always the best or near to the best option
Personally I drive a Rohloff gear hub. But I'm still impressed, that sliding a chain sideways over gears is still such an effektive way to provide gears.
@@chrisridethatbloodything2044It's a case of KISS (Keep it simple stupid) at work. Over engineering doesn't make things better, just more complicated. Go ask the German tank engineers of ww2 how well it worked out for them making overly complex and "advanced" motors and suspension (little hint... they spent more time being repaired than functional)
@@SilvaDreams With a separate supply chain for most of the parts, and being so complicated that they had to be sent back to the factory for a many repairs, at a time when logistics was at a premium. They often couldn't just be cannibalized like a Sherman or a Jeep.
Yup, simplicity just works best. I live in the Netherlands, flooded with bikes, the vast majority with chains and the rest belts. Though you only very rarely crank shafts, despite this system being pretty simple too.
A statisztika alapelve, hogy "a negatív eredmény is eredmény". Magyarán: 1) Ha nem jársz végig egy tévutat, akkor mi igazolja, hogy tévút? 2) Olyan tévút nincs, amiből ne lehetne tanulni. 3) egyébként ez a megoldás pont hogy semlegesíti a holtponton forgatónyomaték problémát.
As a proof of concept it's frankly quite interesting, this clearly was a first gen product. Things like disc brakes, downsizing, efficiency, friction and longevity are addressable. And I'm sure that eventually they could make it so the drums narrower, only on one side, and later on they could even have drums with variable diameters for additional shifting range. But it would need at least another decade of R&D. The problem here being that the inventors patented the technology and kept it to themselves, so it was destined to remain nothing but a short lived curiosity.
@@calebverdu3091 Government is not the problem, it's who's controlling it. When profiteering companies draw the laws to privatize standards and mechanisms we all lose. Open source has benefited our entire society in ways people don't seem to realize. If Microsoft had their way we wouldn't be able to access your documents without buying a recent version of Word. When freedom prevails we all benefit, when not, only a few benefit. We need open source to become de rigueur everywhere.
@@emdivine The profit motive should incentivise them help third parties license and improve their patents especially when they are not using them in their own products. This is not the profit motive it is the idiot motive and it happens everywhere.
There is a company making a velocar/hpv called Djiker that seems to be using a variant of string drive that ditches rotating pedals for linear pedals so the idea lives on.
0:30 I dont like the opening of this video. "Maybe a 'String Drive' bike is the ultimate solution" Uhh solution to what? You laid out a thesis that includes a problem without mentioning it? You never said what is inherently flawed with a chain design.
It is a nice desk contraption to look at. I guess they should push for mechanical home trainers.... No diskbrakes nor motors needed. Like you said: the individual settings for left and right can be adjusted for compensating an injury or assymmetry. I would guess that architects would like to ride these like their SAAB900's back in the days. I' hope the designers are taken in well care so they'll get their chance to hit something viable.
A very good analysis. I had one (probably the only one in Australia) and did not experience any useful advantages. The disadvantages, as shown here, were severe and there were other snags not shown. For example, I found it impossible to start on a hill.The "Dyneema" ropes are meant to hold 1,500 kg but mine held only 110 kg - maybe not real Dyneema - so I was breaking a rope every week or so. Also, you do get dirty hands on changing the strings.
Thanks for the insight. On seeing the marketing shots of super clean strings, it made me think “in real life it would be dirtier”. Not being able to start on a hill is a dealbreaker. Snapping a rope a week = $40 a month, another dealbreaker. And rim brakes? Nope.
They say it can climb. But every single shot of the product in action is on flat terrain. That is a highly reliable bullsh*t indicator. All "innovative" drivetrains have the exact same issue. They work (at least theoretically) on perfectly flat terrain. But they are a nightmare on the hills. The reason the chain drive is so popular is because it works decently in all road conditions. Flat, uphill, downhill, sh*tty road with potholes, etc.
@@illegitimate0 That's what they said - that you can change gears while stationary. But I found that you can't. The lowest gear would get you started halfway up a hill, if you had pre-selected it before you came to the slope. If you were in high gear as you approached the hill, you'd have to go through as many as 18 gear changes before you got to the hill, and gear changes had to be done singly with the pedals in a particular position.
Regarding oval chainrings, I concur, their benefit is inconclusive. I have one on my mountainbike. As said in the video, I didn't notice an efficiency benefit, but I feel it helps to keep grip in very steep slippery climbs. I also get less knee pain than on my round-chainrig bike.
It shows that belt drives are a good option; not sure they are that revolutionary since belts precede chains by a long way, and have never gone away (car fan-belts, etc). Their advantage is that they leverage other developments in bike tech (notably hub gears). I wouldn't say revolutionary so much as an idea whose time has come.
There really isn't enough different about a belt and a chain for a belt to be revolutionary. Digital drive (maybe should be renamed) would be revolutionary if it ever took off.
Planetar gear system + Belt - its best solution. No dirt, no rust, less maintanence, quiet, gear changes when stop, protected from hits, simple design etc.
@@Cyclingabout Wouldn't the best "drivetrain" essentially be similar to a central one-wheel with a gearbox plus front and rear wheel for steering? Basically eliminating belt,chain,string, cardan shaft and instead driving a gearsystem directly. I bet there is a tinkerer that did this. It might also come with rear and front axle steering.
In the Stockholm museum of technology (Tekniska museet) they have a "Svea" bicycle from around 1900 that uses a mechanism related to this string setup, but with an almost standard chain - with a twist. Two twists, in fact! It has two platform "pedals" with curved levers, like the string drive but pure up/down movement (which at the time was presented as an advantage over rotary pedaling). The ends of the chain could be moved up or down curved arms with notches, for "gear changes", with pneumatic actuators from squeeze bulbs on the handlebars. The chain ran over freewheels on both sides of the rear hub, then over an idler in front of the wheel. The chain had two "twist links" allowing the mid section to turn around the idler. The idler was spring loaded away from the wheel and had a platform that was pressed against the tire if you pushed down on both pedals at the same time - very simple braking. I *think* (although this is my conjecture since the museum never got them to work) that the pneumatic actuators would move their respective end of the chain up or down along the curved lever arms, depending on the pedals' position when the rider squeezed the corresponding bulb - "up" if the pedal was in its highest position, "down" if it was in the lowest.
I got to try a bike like this once in Finland. Though I don’t recall whether it had shifting or not. Nice experience, though not very efficient. I think they designed it that way to make it easier to balance yourself while pedalling
I am not entirely sure but: 1) front disk brake is definitely possible 2) rear disk brake is also possible if it's fitted in-between the ropes OR the the calipers are mounted closer to the spokes (not in-line as usually)
Interesting stuff. I use Dyneema cordage in my hammock suspensions and it's a truly amazing material. It doesn't do super well with abrasion though, so I'd be interested in seeing the longevity of this system.
Quoted as 1000km (about 600 miles) which even for pretty light use is multiple changes a year. 6 miles each way 5 times a week (about a 30 min ride, so nothing excessive) is 60 miles a week, so you're potentially changing strings 5 times a year. I suspect that changing the strings 5 times is considerably more hassle than than either regular chain maintenance as you are supposed to, or slightly more involved chain cleaning if you let it slide a bit. Unless you never do anything with your chain until it rusts solid or you need to replace chain, sprockets and chain rings at the same time, and do so frequently, it probably isn't a huge advantage.
@@chrishowell5718 The limited mileage of the Dyneema strings is actually a disadvantage. According to my observation from the film, the time it takes to replace them is significantly shorter than any chain maintenance. 😃
Although dyneema fabric has high tensil strenght it drops significantly when heated up i.e. because of friction. That is why in climbing it advised to refrain from pulling dyneema ropes under load through all sorts of climbing hardware. Maybe this is why these dyneema strings last so short. I wonder how big of a friction there is on the surface of all these pulleys and the rear drum. Also, the string moves a fixed lenght when reciprocating so only several and short stripes make contact with the drums and pulleys and carry the load. This may also contribute to its short longevity. Not a good idea - a bit complicated, unrealiable, clunky, not neat with all these shifting cables.
My takeaways: Elegant, but complicated design, with few real benefits over chain drive. String drive lasts roughly 1/2 as long as a chain You need to change the rear drum for hilly rides (Chain drive just toggles between high and low on the front sproket) People think you can't use a chain in rain/snow (LOL it's called OIL / Maintaining your chain) Being precision machined lever action, one bump will throw it off and damage it. Good luck changing gears with a crooked arm. Bonus: If you are getting oil on your pants when you ride a bike, you're just clueless. And chains are 100% recyclable...is this string recyclable?
I have heard that a fully enclosed drive-train negates chain fouling concerns. There is a weight and efficiency penalty: since you need to use an internally geared hub.
You actually don't need more gears then one to have a practical transport. Before the 60's speeds are not common. My parents have never had a bike with gears, in the Netherlands. They never used it for sport but to get somewhere.
@@albertmagician8613 you also dont need planes to travel to the other side of the world, that doesnt mean its the best way to do it or that it wont be replaced immediately if a better option becomes available
For all the advantages you might think there are to using ropes, the impact of getting a rope dirty is actually _huge._ Even if you clean the ropes after they get dirtied, you're still looking at a minimum of 30% increased wear from that point on, and if they aren't cleaned properly then they might wear out as much as 4x faster than normal. That increased wear is the real reason why they have to use such expensive ropes that can withstand so much more than almost any bike is ever subject to. Considering that the ropes are on a bicycle and completely exposed, they're going to be dirty practically the entire the time the bike is in use.
The design and engineering nerd in me loves these sorts of videos, and it’s interesting to see where the bike industry might go. At the same time, while the video is good, the long distance tourer in me is horrified at all the possibilities for failure in the real world on this particular idea, especially under muddy conditions.
Just had to check todays date. Phew, it’s not April 1st. The major downside to this system would be mud, here in the UK we get a lot of rain, so far we’ve had 3 major storms in the last month alone. So lots of leaves and general muck on the roads means riding and more importantly, cornering speeds, are not what they were. Whilst I see no MTBs, I’ll bet off-road and you’d be in for a lot of hike-a-bike, or even pushing it home an/or back to the car. I take it wouldn’t take a tumble well would it? Anything bent or misaligned around the BB area and I’d’ve thought it was a game over.
If Sheldon Brown were alive today, I'd be really keen to hear his take on this. I know he was a fan of elliptical/near elliptical chainrings (like Biopace), and he didn't seem the type to dismiss new technologies with the 'This is the way we've always done it' line.
The rewinding action of the string is springloaded. Thus you are ALWAYS pushing against 2 springs. They may be weak (they only need to rewind the strings), but, still, they are there.
I imagine you could do something similar with belts instead of strings for better durability, but the incompatibility with standard frames is a killer. You could likely say the same thing about systems that use a geared rod instead of a chain too.
I don’t think I could ever get used to the non-linear pedaling effort/power output be revolution. Maybe I did not give oval chain rings enough of a chance. Interesting idea though and probably worthy of further investigation
Very interesting to hear an in depth dive into this tech, it has intrigued me since I came across it. So the answer is it was a dead end, though well worth developing. I did wonder if it would be the answer for a recumbent bike with their very long chains, but the lack of gear range counts that out.
12:45 - tensile strength is necessary to propel the bike, but as you point out, that requires relatively low tensile strength anyway. Possibly more importantly, for longevity and resistance to wear and tear, would be shear strength of the material so that it doesn't break due to knocks, road debris, etc - and on that front I think the chains might have the advantage.
A sting drive where strings last around 1000km and there are steel wirres that will corrode as well definitely is not free of maintenance. 😉 A nice design anyway!
I live in the Netherlands, a nation flooded with bikes, and yet I've never seen this system before. I guess it hasn't been introduced here, but I am pretty sure strings wouldn't have taken off anyway. Perhaps a few people wanting something quirky would buy it. It's all chains and ever more belts, and on very rare occasions a crank shaft.
I ride my bicycle as my main form of transportation all year, all weather, all the time, because I prefer it to my car. I like this idea, but for me, the downfall is that grit severely affects longevity, at least according to you. The ropes will become coated in salt in the winter and even if I cleaned them they would get coated in salt again within a couple of miles. One day, I hope to have a belt-drive gearbox system. My traditional drivetrain takes a lot of maintenance, even though I don't use a front derailleur. It gets irritating sometimes. Especially in the winter, when the air is too harsh to work outside.
I don't get the disk brake argument. Yes, you can't put a disk on the rear, but you can still make a mullet with a disk on the front and rim brake on the rear.
agreed rim brakes are more than suffecent for locking up the rear wheels and the other downsides of wear and cooling do exist but you shouldnt be using your rear brakes enough to make that a concern
I’m amazed you manage to put out quality content like this while cycling around the world. I guess Stellenbosch has better connectivity than some of the areas you’ve been through lately!
same like all western tech , to many moving parts , a bit of dirt and reality , and you had a drivetrain in prestine settings for sure a nice idea to build up on
Not sure that there is a need to improve on the chain drive. It works, it is reliable, it is low maintenance. Anything more complicated is not good here.....
Don´t forget those roller coaster wheels! They will wear out and cost alot of friction! I think the belt drive combined with internaly geared motor units will be the futur for alot of bikes like city- and mountinbikes. For roadies the chaindrive will stay the gold standard because of its superb low friction and light waight.
I stopped at 0:50...More mechanical points of failure, weaker materials, more susceptible to damage and debris, more friction points...It's clear that this is a terrible design by someone who is trying to reinvent the wheel just for the sake of being different rather that improvement.
it seems very complex and sensitive to change, and that appears to be the most simple that mechanism can be. as an engineer, my first thought was KISS (Keep It Simple Stupid), and this doesn't seem to be the simplest you could design something like this. it may have it's upsides, but I'll trust that the chain on my bike won't snap, and if anything breaks i can replace it easily, quickly and cheaply, and even on the road. dynema is also notorious for performing poorly when heated, so i would trust it even less on a hot day, or riding particularly hard. you mentioned wide gears as one of chain derailleur systems' downsides, but often people want extremely wide gears, especially for road cycling, where the hills can be very steep, but you also may need to ride fast. overall, too complex, too proprietary, too weak, too sensitive, not trustworthy, and incompatible with other technologies. ima stick with my chains :P
Indeed and i think the starting position is not optimal, if i put my foot on it i want it to be in a position where i have a long way to put force into so 2 o clock, then i can use my whole weight for the first stroke, if id use the position in the video(4o clock) id have a lot less acceleration for the start. And if we watch bike races we see thats how most people start. 2o clock or slightly above the best conversion point at 3 o clock, where gravity helps the most.
I considered buying one of these a couple of years ago, but the narrow gear range was a deal-killer. The high price and weird bespoke frame were also turn-offs. I eventually purchased a belt-drive bike with an 11-speed rear hub which was much cheaper, weighed about the same, and had a better gear-ratio spread.
4:41 this is probably the coolest feature 10:49 you don't need different size drums, since the gear setting on each side is independant (and yes they DO need adjustment 1:10) thanks for sharing!
Thank you so much for the education on string drive. Never heard of this before, but now I wish it had succeeded, and they lasted for 10x longer, and allowed for electrification, too! It all just seems way better than exposed chain; which we've been using for so long now. Surprised to see there aren't even more types of bikes available out there today. AI might soon change that though.
@@gaoxiaen1 Thankfully no engineers think like you. We wouldn't have cell phones, commercial jets, computers and a million other things that came along after 150 years ago...
@@BitBuhkit Me neither. It's just that sometimes the best practical soltions have been worked out long ago. Yes, in some circumstances there are better devices that can be used, but I don't see things like the screw, the nail, the bolt and nut, the table and chair, the metal can and glass or plastic bottle, etc... going away soon. Yes, the string bicycle is an interesting novelty. So is the hubless wheel for motorcycles and turbine engine car and many other inventions, but it takes a long time to replace a tried and true practical solution. Fuel injection (of whatever type) and overhead valves for gasoline engines used to be exotic and futuristic, but have only become commonplace in the last few decades. Most inventions remain only novelties.
It almost feels like you could rehash this tech using standard-ish ebike frames. I don't know if the geometry works, but if you could build a unit that bolts into the space a Bosch ebike motor (or similar) uses, it'd be an interesting idea. One-sided, of course, maybe even something that fits on a HG freehub.
Its amazing how far engineers will go to solve the problems of bicycle chains, hefore they resort to the obvious solution - a chain cover!!!! Honestly, my daughter's bike has an almost entirely enclosed drive train, and i basically never have to clean it. She's ridden it thousands of miles now with no issue. I wish adult bikes came with enclosed drivetrains more often.
Exactly. I've been advocating drivetrain fairings forever. Why do they say a rear derailleur gets dirty but a IGH does not? So helpless. Just cover it up, then it won't get dirty.
You can use a full chainguard with a single speed bike, or with internal gears, but not with a derailleur. Oh, I suppose someone could design some montrousity that would fit over a derailleur, but I think it would create other problems.
Wow half way into the video these seem like they solve every single issue i have with normal bikes, cant wait for these to be common, unless there is a big catch coming in the second half haha
The design reminds me of the elliptical trainer used in the gym. The device has the option to use leg pedals along with reciprocating handles which resemble the reciprocating motion of the string drive. I often used the elliptical trainer and increased the resistance (compared to higher gear ratio in bikes) by holding the handles closer to the hub, i.e. lower. In my opinion something similar can be used for hand bikes (used by people with lower body paralysis, who cannot pedal). Reciprocating handles would make full use of the simplicity of the string drive because no spinning pedals are required. The hand-cyclist can adjust the gear ratio simply by changing his hands position: Low gear is achieved by holding the top part of the handle. Holding lower can increase the gear ratio.
Some time about 1974-1976 one of the bicycle magazines in the US had an article on a cable drive bike. What is shown in this vid looks very familiar to my memory from five decades ago.
I think they went with string for two reasons: 1) It's not going to wear the other surfaces, it'll wear out first, and 2) It's not particularly dangerous if it snaps. This could certainly be designed with other materials, but you'd either end up with immense wear and tear on other parts, or danger if it did snap under tension. I feel like they could have probably made these far more robust though in a few ways, like for example, having a metal spring core in the strings, while also making the string thicker. I could imagine for example, a string in the center, wrapped with a metal spring, and then an outer rubbery layer added or something like that, giving it a lot of flexibility and durability.
4:30 not true for a lot of internal gear hubs, with most of them you're not supposed to or just cannot shift under load and you only can while stationary. So the string drive definitely has an advantage there. As for an ebike string drive, why not just put the electric motor on the front hub?
I wonder if some kind of coated wire would work better than the strings? As far as using disc brakes on the back wheel, a solution would be to build it around the wheel hub -- inside the spokes -- with a wireless control that could clamp on it for braking.
I use dyneema rope on my atv winch. It works great and, like he said, it floats. That’s nice when tossing across some water and the hook doesn’t quite make it to shore.
I'm curious about the efficiency of this. Since it goes against a simple principle of reducing parts (under the assumption that the bike chain is "1 part"). Now we have 2 drive chains, cams, pulleys and winches. Basically more than doubling the amount of bearings, and while strings are way more smooth and efficient in transferring energy than a chain. Having a reciprocating winch and cam system seems to add a lot of friction to the system. Especially the winches, which have to coast 50% of the time. Seeing the shaft torque to wheel torque compared between belts chains and strings (or any other system) would be extremely interesting.
I like how it couldve changed the bike industry. Unfortunately we cant find this option but i appreciate continuous effort of scientists and engineers and designers to constantly reinvent things so we have better and various options. Thank you for geeat video
Noticed that only regular bikes have gear adjustment cables between seat tube and rear wheel, forcing for longer wheelbase. Those performance bikes have been set up other way to pull gearing cables.
*Summary* * *00:00:37** String Drive Basics:* Bikes with a drivetrain using Dyneema ropes instead of a chain, produced from 2011-2021. * *00:01:54** How it Works:* Pedaling moves lever arms that pull ropes attached to the rear wheel, winding and unwinding on drums. * *00:00:58** Key Features:* * *00:00:58* Grease and oil-free * *00:01:04* 19 gears * *00:01:04* Shifting while stationary * *00:01:11* No gear adjustments needed * *00:02:19* Ropes are stronger than chains * *00:03:46** Advantages:* * *00:03:46* Smooth and silent operation * *00:03:52* Virtually no maintenance * *00:04:23* No derailleur to damage * *00:04:42* Automatic favorable pedal starting position * *00:04:54* Only consumable is the rope (cheap and easy to replace) * *00:05:15* Minimizes "crank dead spot" for potentially better efficiency * *00:05:39* Easy rear wheel removal * *00:06:05* Closely spaced gear ratios * *00:06:36** Disadvantages:* * *00:06:36* Requires a special frame * *00:06:56* Proprietary components * *00:07:09* Incompatible with disc brakes and e-bikes * *00:07:43* Shorter rope lifespan than chains or belts (1000-2000 km) * *00:08:08* Grip shifter can be stiff and doesn't integrate well with drop bars * *00:08:28* Heavier than derailleur systems (~1 kg more) * *00:08:35* Potentially less efficient than chain drive * *00:09:17* Smaller gear range than modern drivetrains * *00:10:32** Quirks:* * *00:10:32* Can pedal backwards to move forward * *00:10:44* Allows different gear ratios for each leg * *00:10:56* Reduced "crank dead spot" effect (like oval chainrings) * *00:09:46** Why it Failed:* Ultimately, the proprietary nature, incompatibility with emerging technologies (disc brakes & e-bikes), and the rise of strong alternative drive systems (belts, internal gear hubs) led to its demise. *In essence, String Drive was an innovative, clean, and low-maintenance drivetrain solution that was unfortunately hampered by its proprietary design and the timing of its release, coinciding with the rise of other competitive technologies in the cycling industry.* I used Google Gemini 1.5 Pro exp 0801 to summarize the transcript. Cost (if I didn't use the free tier): $0.0421 Time: 34.47 seconds Input tokens: 8602 Output tokens: 1142
That was an interesting description. I might mention though that every problem listed can be fixed. This includes: Adaptation to existing bike frames. Wider gear ratio. Compatibility with disk brake. Greater wear life for cord. Lever based or automatic rather than twist grip shifter.
the wider gear ratio as in the range from the highest gear to the lowest not how many gears i would also like to mention that disc brakes are not nessary in the rear because of wheight transfer when you brake and rim brakes are more than cabible of locking up the rear tire but disc brakes are nessary for the front but they can install them anyways since there is noting preventing them.. note i do know that there are other benifits to disc brakes for example not chewing through wheels longer brake pad life as well as better distribution of heat but if you are using your rear brakes enough to where thats a concern there are different issues
Fun video, and fun concept! It seems like the pedal parts rubbing against the inside of that shape would cause significant issues, especially if any dust got in there, which it instantly would. Didn't hear that mentioned in the video for some reason ...
Very close gear ratios require frequent shifts. I found that large gear gap help us pedal more efficiently across a broad rmp range. Single speed racers often outperform cyclists with gears, especially on section with speed fluctuations, where you'd think you need the gears the most. I've found it ideal to have few gears, and use each for a "scenario". One tailwind or the road, or a fast downhill, maybe sprints. Two for spirited flat road or offroad flat racing. Three for undulating low elevation change, winding singletrack. Four for climbs too long to sprint up in 3rd. Five for really long climbs or very technical climbs. Six would be for hour-long super steep off-road clibs, or low effort road climbs. You'd hardly ever shift. Our legs can handle walking and sprinting, they'll be fine.
The efficiency of a rotary engine can exceed 45%. The efficiency of the piston engine is 30% in an ideal design. Circular motion is much more effective than reciprocating motion. Maybe you could also suggest replacing the metal bearings with wooden bushings with tar?
Fascinating. The persistence of chain drives after 150 years lies in the surprisingly low overall frictional losses, especially with the refinement of chains themselves, optimized cogs, and good old wax as the basis for the best, easily maintained lubricant. Motorcycles with drive shafts have far higher frictional losses, only offset by sealed systems, and the power to spare from an engine other than a human. This design also has many more pivoting bearings, likely needing service or replacement.
The concept looks interesting at first glance, but overall it doesn't convince me. too wide, too many parts in the bottom bracket area and just as susceptible to dirt as chains. ... well.
chain drive is more efficient. Ropes stretch when torque is applied thus using part of the energy for stretching the rope and not for propulsion. Some motorcycles use a kevlar rubber belt which is stiffer than rope.
This is for what? For drive in a park on a weekends? Everyone constantly forgets that a bicycle is not only a ride in a straight line. How will this work for example in the forest? Among the pits and roots? This is a 'one of' example.
I think they needed the extra tensile strength, because the force on the string is way higher than with a chain because it just pulls half of the time but then with double the force i think.
It would be worth testing here in Bavaria in winter, (where many of us continue to bike to work even in the snow with the appropriate winter tyres or simply with the MTB). From the point of view of pedalling efficiency it is one of the solutions to avoid pedalling deadlocks (in France a century ago a two-way pedalling system with two chains with two sets of different ratios was also tried out) but I would have doubts about long-term reliability and daily use on all kinds of road surfaces and different climatic situations. Especially for dirt and foreign bodies that can interfere with such a system. The linkage and cable drive system is ingenious (although there are analogies in applications on industrial machines) but I find it complicated to manage in terms of reliability and maintenance
Though this drive train is maybe not the best for bicycles it would probably be very well suited in therapeutics as a stationary bike that offers different levels of difficulty for each leg. Allowing a weaker leg the ability to train up to the stronger leg (and maybe make both legs stronger).
String spokes on both Olympic Gold medal winners XC bikes brought me here. I was wondering how long those spokes last? I was also wondering if strings could be adapted somehow to a deraileur with pulley wheels and pulleys instead of a chain driven cassette?
There's a LOT of research & development going on in the CVT, digital drive, combined motor+gearbox, and hydraulic drive spaces! What bicycle drivetrain tech would you like me to cover next? 🎉
Hydraulic sounds interesting
What's CVT?
I love your videos on non traditional gear. I share your passion for belt drive bikes. But this tech I feel is not going anywhere. No disc brake + not good for e-bikes tells me that.
@@pumpkinjutsu1249
A single gear transmission that is a continuous variable transmission. Many automobiles use them now.
@@pumpkinjutsu1249 "Continuously Variable Transmission: A continuously variable transmission is an automated transmission that can change through a continuous range of gear ratios. This contrasts with other transmissions that provide a limited number of gear ratios in fixed steps."
I wouldn't want to park one of those in any city that had developed scissor technology.
Tweakers/FentHeads in San Francisco (where I live) would cut those strings on purpose, out of spite, just cause they're there.
tbh with a good pliers I can also cut down chains
I also thought it weird that this most obvious flaw wasn't adressed
I fail to see how the strings are more vulnerable than your tires, though...
Because the novel unusual strings, when seen, put the idea into the head of nasty person.
@@Jerburger
I really love seeing people just trying to do something different, whether it ends up working or not.
Agreed, it might not takeover chains anytime soon but it's interesting new way to pedal a bike.
If it ain’t broke…
thats what im sayin @@idonjohnson6999
Agreed. So many technologies we take for granted nowadays came from someone asking "what if...?"
There was nothing wrong with horses, but life is a hell of a lot better with a car.
I've had a Stringbike a few years ago. It was really finicky to adjust, and those D-shaped things could bend really easily during transport, the complete system seemed to be very complicated and sensitive. Pedaling on it was not bad though, but I think the conception created more problems instead of solving them. Btw the website went down a few months ago, I think they don't exist anymore...
It’s so niche, if mainstream they’d probably work the kinks out.
Thanks for the insight regarding the lever arms, and adjustment! I actually used one for a while in 2012, although that was not long enough to find any issues. I thought it felt nice to ride once I'd adjusted to the elliptical driving path.
looks like sticks would easily get twisted in the strings. the cords would rot before a chain. not so avoidable. @@danparish1344
No shit.... they have re-invented to wheel... but its square..... and trying to convince you its not....
Yes, they went bankrupt a few years ago. The bike industry pushed them out and the selling number was low. I never tried, but theoretically, it brought a better (and, yes unusual) pedaling result.
So, it's funny. The video is about an already fallen concept and excited about it.
Love the out of the box thinking with the string bike. Dyneema is used as an alternative to stays and shrouds on a sailboat to keep masts up, so that hints at how strong this line is.
I clearly see metal pedals moving against metal part - there will be wear and tear as well as energy loss or may be sound in case of moisture.
The other limiting factor for the technology was the company who owns the patent for it. One of my relatives wanted to do business with them as the drivetrain would have been ideal for the particular use case (not a bike). He said they were not flexible in improving or adopting the idea, they created terrible quality of products and in general, were really hard to work with. So they ditched the idea and stayed with a regular chain drivetrain.
Oh well maybe it will be useful whenever the patents run out if it is even remotely relevant at that point and somebody finds out/remember that it was a thing
Society is better with open standards and open information.
Everybody wants to get filthy stinking rich right now.
@@oneofthesixbillion yeah but then no one in their right mind would ever invent anything. It takes years of effort,countless failed attempts to come up with something that works, and then works efficiently, and then works at cost.
Then you have a bozo that comes after and copies it. We would have no innovation and people who would invent would never share it to a public avenue in that case.
The opposite would happen
To increase competition all patents should be on an open licence, as long as something like 10% of the product price is paid as royalty fees there is no violation.
I love the way you analyze, examine, think through, organize your presentation, state your case...everything. I have been looking for an exposé on string drives for a couple of years, and this covers everything I wanted to know. Thanks, and all the best.
I owned one of these, bought it second hand. The gear cables are a pig to fit and need special gear wires at the cranks which took forever to get from Hungary (I'm in the UK). The shifter uses two standard gear cables wrapped around a cylinder inside the shifter. Then there was the issue of balancing the gears on the cranks so gears changed in synch on each side. Effectively there were six cable ends to secure and balance at the bottom bracket: two cables coming from the shifter and the two ends of the two special gear wires, one on each crank. I sold it to a friend and he still rides it but getting replacement cords and other spares is a real problem.
I was thinking that at minimum there must be some synchronizing issue with the shift cables between the two sides!
Well, that seems prohibitively technologically limiting and challenging in daily use/maintenance.
sounds like the claim of needing 'no gear adjustment' isn't quite true....
Not in my experience of having one for a year or so! @@adriansue8955
He should be able to get a dyneme line and make his own cords. It's not a big deal. I would love to have one. I'm weird that way. I own Windcheetah.
modern belts can last upwards to 30k km.... well certainly not the Gates CDN, mine gave up under 2k km and after that i researched and many had the same issue. turns out Gates be like "yeah that ones not for actual use. only on tarmac with no gradient and no dirt and if you dont drive much and dont go fast." what a piece of junk. always get the CDX if you want a real belt.
i have a clssical mountain bike with chain drive, which i have been using for 25 years, never changed the chain. actually never even oiled the damn thing.
so 1000 km to 2000km range of duration for the strings seemed a litle bit short to me.
I think it’s really cool, if only for the mechanical novelty aspect of it. The fact that it worked as well as it did, is testament to the team’s knowledge and hard work. Unfortunately, for it to work for the masses, it needs to be much easier to work with, cheaper, and have wider compatibility. Great video once again. Cheers from Australia
yeah string drives have their advantages I like having the choice of which ever one I want to use on a bike chain or string drive cause choice plain and simple
@@SaraMorgan-ym6ue That’s true, the more choices the better.
It's kind of like that Kick 'n' Go scooter that had a pedal behind you you could pump to get going, but it only had a little success for about 2 or 3 years and the concept dropped. Nobody else took it up and ran with it. It didn;t really sell more scooters.
I agree. It's a cool idea. Maybe it can be used in a different application. Hi from California.
It's sort of used in garage doors lol
I find it so interesting that every one of these videos about different drivetrains always come to the same conclusion : belt drives are sometimes the best option, chains are almost always the best or near to the best option
Personally I drive a Rohloff gear hub. But I'm still impressed, that sliding a chain sideways over gears is still such an effektive way to provide gears.
@@chrisridethatbloodything2044It's a case of KISS (Keep it simple stupid) at work. Over engineering doesn't make things better, just more complicated. Go ask the German tank engineers of ww2 how well it worked out for them making overly complex and "advanced" motors and suspension (little hint... they spent more time being repaired than functional)
@@SilvaDreams With a separate supply chain for most of the parts, and being so complicated that they had to be sent back to the factory for a many repairs, at a time when logistics was at a premium. They often couldn't just be cannibalized like a Sherman or a Jeep.
Yup, simplicity just works best. I live in the Netherlands, flooded with bikes, the vast majority with chains and the rest belts. Though you only very rarely crank shafts, despite this system being pretty simple too.
A statisztika alapelve, hogy "a negatív eredmény is eredmény".
Magyarán:
1) Ha nem jársz végig egy tévutat, akkor mi igazolja, hogy tévút?
2) Olyan tévút nincs, amiből ne lehetne tanulni.
3) egyébként ez a megoldás pont hogy semlegesíti a holtponton forgatónyomaték problémát.
As a proof of concept it's frankly quite interesting, this clearly was a first gen product. Things like disc brakes, downsizing, efficiency, friction and longevity are addressable. And I'm sure that eventually they could make it so the drums narrower, only on one side, and later on they could even have drums with variable diameters for additional shifting range. But it would need at least another decade of R&D. The problem here being that the inventors patented the technology and kept it to themselves, so it was destined to remain nothing but a short lived curiosity.
Yep, an example of when the profit motive hampers innovation.
The profit motive could not stifle innovation without the help of government. The policies of government reflect the values of society as a whole.
@@calebverdu3091 Government is not the problem, it's who's controlling it. When profiteering companies draw the laws to privatize standards and mechanisms we all lose. Open source has benefited our entire society in ways people don't seem to realize. If Microsoft had their way we wouldn't be able to access your documents without buying a recent version of Word. When freedom prevails we all benefit, when not, only a few benefit. We need open source to become de rigueur everywhere.
@@emdivine The profit motive should incentivise them help third parties license and improve their patents especially when they are not using them in their own products. This is not the profit motive it is the idiot motive and it happens everywhere.
There is a company making a velocar/hpv called Djiker that seems to be using a variant of string drive that ditches rotating pedals for linear pedals so the idea lives on.
0:30 I dont like the opening of this video. "Maybe a 'String Drive' bike is the ultimate solution" Uhh solution to what? You laid out a thesis that includes a problem without mentioning it? You never said what is inherently flawed with a chain design.
It is a nice desk contraption to look at. I guess they should push for mechanical home trainers.... No diskbrakes nor motors needed. Like you said: the individual settings for left and right can be adjusted for compensating an injury or assymmetry. I would guess that architects would like to ride these like their SAAB900's back in the days. I' hope the designers are taken in well care so they'll get their chance to hit something viable.
A very good analysis. I had one (probably the only one in Australia) and did not experience any useful advantages. The disadvantages, as shown here, were severe and there were other snags not shown. For example, I found it impossible to start on a hill.The "Dyneema" ropes are meant to hold 1,500 kg but mine held only 110 kg - maybe not real Dyneema - so I was breaking a rope every week or so. Also, you do get dirty hands on changing the strings.
Thanks for the insight. On seeing the marketing shots of super clean strings, it made me think “in real life it would be dirtier”. Not being able to start on a hill is a dealbreaker. Snapping a rope a week = $40 a month, another dealbreaker. And rim brakes? Nope.
They say it can climb. But every single shot of the product in action is on flat terrain. That is a highly reliable bullsh*t indicator.
All "innovative" drivetrains have the exact same issue. They work (at least theoretically) on perfectly flat terrain. But they are a nightmare on the hills.
The reason the chain drive is so popular is because it works decently in all road conditions. Flat, uphill, downhill, sh*tty road with potholes, etc.
They said you can change gears when stationary. So why couldn't you use it on a hill? Is the lowest gear too high?
@@illegitimate0 That's what they said - that you can change gears while stationary. But I found that you can't. The lowest gear would get you started halfway up a hill, if you had pre-selected it before you came to the slope. If you were in high gear as you approached the hill, you'd have to go through as many as 18 gear changes before you got to the hill, and gear changes had to be done singly with the pedals in a particular position.
Regarding oval chainrings, I concur, their benefit is inconclusive. I have one on my mountainbike. As said in the video, I didn't notice an efficiency benefit, but I feel it helps to keep grip in very steep slippery climbs. I also get less knee pain than on my round-chainrig bike.
If anything, this shows us exactly what a revolutionary idea the Belt Drive was.
It shows that belt drives are a good option; not sure they are that revolutionary since belts precede chains by a long way, and have never gone away (car fan-belts, etc). Their advantage is that they leverage other developments in bike tech (notably hub gears). I wouldn't say revolutionary so much as an idea whose time has come.
There really isn't enough different about a belt and a chain for a belt to be revolutionary. Digital drive (maybe should be renamed) would be revolutionary if it ever took off.
yeah I agree on dialing down the "revolutionary" bit. Unless that was merely a pun.
@@chrishowell5718 And the main drive system for Harley Davidson for decades.
wtf is wrong with regular chain jesus christ poeple cmon
Planetar gear system + Belt - its best solution. No dirt, no rust, less maintanence, quiet, gear changes when stop, protected from hits, simple design etc.
This is the first video I've watched on your channel. The quality of production is remarkable.
It looks goofy and awesome at the same time :D Thanks for exposing the hotest new stuff in bikes!
It's definitely one quirky drivetrain! I hope we see more of this weirdness in the future. ⚡️
@@Cyclingabout Wouldn't the best "drivetrain" essentially be similar to a central one-wheel with a gearbox plus front and rear wheel for steering?
Basically eliminating belt,chain,string, cardan shaft and instead driving a gearsystem directly. I bet there is a tinkerer that did this.
It might also come with rear and front axle steering.
In the Stockholm museum of technology (Tekniska museet) they have a "Svea" bicycle from around 1900 that uses a mechanism related to this string setup, but with an almost standard chain - with a twist. Two twists, in fact!
It has two platform "pedals" with curved levers, like the string drive but pure up/down movement (which at the time was presented as an advantage over rotary pedaling). The ends of the chain could be moved up or down curved arms with notches, for "gear changes", with pneumatic actuators from squeeze bulbs on the handlebars. The chain ran over freewheels on both sides of the rear hub, then over an idler in front of the wheel. The chain had two "twist links" allowing the mid section to turn around the idler. The idler was spring loaded away from the wheel and had a platform that was pressed against the tire if you pushed down on both pedals at the same time - very simple braking.
I *think* (although this is my conjecture since the museum never got them to work) that the pneumatic actuators would move their respective end of the chain up or down along the curved lever arms, depending on the pedals' position when the rider squeezed the corresponding bulb - "up" if the pedal was in its highest position, "down" if it was in the lowest.
I got to try a bike like this once in Finland. Though I don’t recall whether it had shifting or not. Nice experience, though not very efficient. I think they designed it that way to make it easier to balance yourself while pedalling
Fantastic review very balanced.
Thanks for watching!
Great to be able to adjust left/right torque ratios independently. Could be very useful in physical therapy and sports training.
I am not entirely sure but:
1) front disk brake is definitely possible
2) rear disk brake is also possible if it's fitted in-between the ropes OR the the calipers are mounted closer to the spokes (not in-line as usually)
Interesting stuff. I use Dyneema cordage in my hammock suspensions and it's a truly amazing material. It doesn't do super well with abrasion though, so I'd be interested in seeing the longevity of this system.
Quoted as 1000km (about 600 miles) which even for pretty light use is multiple changes a year. 6 miles each way 5 times a week (about a 30 min ride, so nothing excessive) is 60 miles a week, so you're potentially changing strings 5 times a year. I suspect that changing the strings 5 times is considerably more hassle than than either regular chain maintenance as you are supposed to, or slightly more involved chain cleaning if you let it slide a bit. Unless you never do anything with your chain until it rusts solid or you need to replace chain, sprockets and chain rings at the same time, and do so frequently, it probably isn't a huge advantage.
No one asked you
@@DoraExploring-ls5vf I bet you're fun at parties.
@@chrishowell5718 The limited mileage of the Dyneema strings is actually a disadvantage. According to my observation from the film, the time it takes to replace them is significantly shorter than any chain maintenance. 😃
Although dyneema fabric has high tensil strenght it drops significantly when heated up i.e. because of friction. That is why in climbing it advised to refrain from pulling dyneema ropes under load through all sorts of climbing hardware. Maybe this is why these dyneema strings last so short. I wonder how big of a friction there is on the surface of all these pulleys and the rear drum. Also, the string moves a fixed lenght when reciprocating so only several and short stripes make contact with the drums and pulleys and carry the load. This may also contribute to its short longevity. Not a good idea - a bit complicated, unrealiable, clunky, not neat with all these shifting cables.
My takeaways: Elegant, but complicated design, with few real benefits over chain drive.
String drive lasts roughly 1/2 as long as a chain
You need to change the rear drum for hilly rides (Chain drive just toggles between high and low on the front sproket)
People think you can't use a chain in rain/snow (LOL it's called OIL / Maintaining your chain)
Being precision machined lever action, one bump will throw it off and damage it. Good luck changing gears with a crooked arm.
Bonus: If you are getting oil on your pants when you ride a bike, you're just clueless. And chains are 100% recyclable...is this string recyclable?
I have heard that a fully enclosed drive-train negates chain fouling concerns. There is a weight and efficiency penalty: since you need to use an internally geared hub.
You actually don't need more gears then one to have a practical transport. Before the 60's speeds are not common. My parents have never had a bike with gears, in the Netherlands. They never used it for sport but to get somewhere.
it's what is often called: "a solution looking for a problem"
@@albertmagician8613
you also dont need planes to travel to the other side of the world, that doesnt mean its the best way to do it or that it wont be replaced immediately if a better option becomes available
No grease and oil? What about the bearings on the crank?
For all the advantages you might think there are to using ropes, the impact of getting a rope dirty is actually _huge._ Even if you clean the ropes after they get dirtied, you're still looking at a minimum of 30% increased wear from that point on, and if they aren't cleaned properly then they might wear out as much as 4x faster than normal. That increased wear is the real reason why they have to use such expensive ropes that can withstand so much more than almost any bike is ever subject to. Considering that the ropes are on a bicycle and completely exposed, they're going to be dirty practically the entire the time the bike is in use.
The design and engineering nerd in me loves these sorts of videos, and it’s interesting to see where the bike industry might go. At the same time, while the video is good, the long distance tourer in me is horrified at all the possibilities for failure in the real world on this particular idea, especially under muddy conditions.
Just had to check todays date. Phew, it’s not April 1st.
The major downside to this system would be mud, here in the UK we get a lot of rain, so far we’ve had 3 major storms in the last month alone. So lots of leaves and general muck on the roads means riding and more importantly, cornering speeds, are not what they were. Whilst I see no MTBs, I’ll bet off-road and you’d be in for a lot of hike-a-bike, or even pushing it home an/or back to the car.
I take it wouldn’t take a tumble well would it? Anything bent or misaligned around the BB area and I’d’ve thought it was a game over.
If Sheldon Brown were alive today, I'd be really keen to hear his take on this. I know he was a fan of elliptical/near elliptical chainrings (like Biopace), and he didn't seem the type to dismiss new technologies with the 'This is the way we've always done it' line.
Would steel cable be a reasonable alternative for the string rope?
it seems there is some bending around the middle of the string
The rewinding action of the string is springloaded.
Thus you are ALWAYS pushing against 2 springs. They may be weak (they only need to rewind the strings), but, still, they are there.
I imagine you could do something similar with belts instead of strings for better durability, but the incompatibility with standard frames is a killer. You could likely say the same thing about systems that use a geared rod instead of a chain too.
are belts also incompatible? you need a split in the frame
I don’t think I could ever get used to the non-linear pedaling effort/power output be revolution. Maybe I did not give oval chain rings enough of a chance. Interesting idea though and probably worthy of further investigation
Very interesting to hear an in depth dive into this tech, it has intrigued me since I came across it.
So the answer is it was a dead end, though well worth developing.
I did wonder if it would be the answer for a recumbent bike with their very long chains, but the lack of gear range counts that out.
Yes, those reload bonuses can be a lifesaver, especially when you hit a rough patch. Helps to keep playing without breaking the bank
12:45 - tensile strength is necessary to propel the bike, but as you point out, that requires relatively low tensile strength anyway. Possibly more importantly, for longevity and resistance to wear and tear, would be shear strength of the material so that it doesn't break due to knocks, road debris, etc - and on that front I think the chains might have the advantage.
imagine replacing transmission parts every 1000km
sell it before 1k
I mean my chain lasted only 2300km
A sting drive where strings last around 1000km and there are steel wirres that will corrode as well definitely is not free of maintenance. 😉 A nice design anyway!
I live in the Netherlands, a nation flooded with bikes, and yet I've never seen this system before. I guess it hasn't been introduced here, but I am pretty sure strings wouldn't have taken off anyway. Perhaps a few people wanting something quirky would buy it. It's all chains and ever more belts, and on very rare occasions a crank shaft.
I ride my bicycle as my main form of transportation all year, all weather, all the time, because I prefer it to my car. I like this idea, but for me, the downfall is that grit severely affects longevity, at least according to you. The ropes will become coated in salt in the winter and even if I cleaned them they would get coated in salt again within a couple of miles. One day, I hope to have a belt-drive gearbox system. My traditional drivetrain takes a lot of maintenance, even though I don't use a front derailleur. It gets irritating sometimes. Especially in the winter, when the air is too harsh to work outside.
Discovered this channel thru this video completely randomly. Glad I clicked. Truly an interesting and informative channel
I don't get the disk brake argument. Yes, you can't put a disk on the rear, but you can still make a mullet with a disk on the front and rim brake on the rear.
Most of your braking power is on the front, anyway.
agreed rim brakes are more than suffecent for locking up the rear wheels and the other downsides of wear and cooling do exist but you shouldnt be using your rear brakes enough to make that a concern
It also has springs to tension the ropes. Those springs need to be overcome to pedal, so that's also a loss in efficiency.
and the reciprocating mass on the spools
I’m amazed you manage to put out quality content like this while cycling around the world. I guess Stellenbosch has better connectivity than some of the areas you’ve been through lately!
That’s a great idea! Betting is always more fun with friends around, and those bonuses for referring them seem pretty generous.
same like all western tech , to many moving parts , a bit of dirt and reality , and you had a drivetrain
in prestine settings for sure a nice idea to build up on
This bicycle lecturer is an amazing explainer; fascinating stuff.
Thanks! I love researching these topics and sharing my findings.
That endurance racer wasn't doing those 262-mile days because of the string drive. He was a real(!) cycling athlete.
my normal $60 10 speed mountain bike has lasted me 30 years with only needing tyre changes.
gg
Not sure that there is a need to improve on the chain drive. It works, it is reliable, it is low maintenance. Anything more complicated is not good here.....
Don´t forget those roller coaster wheels!
They will wear out and cost alot of friction!
I think the belt drive combined with internaly geared motor units will be the futur for alot of bikes like city- and mountinbikes.
For roadies the chaindrive will stay the gold standard because of its superb low friction and light waight.
I stopped at 0:50...More mechanical points of failure, weaker materials, more susceptible to damage and debris, more friction points...It's clear that this is a terrible design by someone who is trying to reinvent the wheel just for the sake of being different rather that improvement.
Lmao, you're hilarious
Watch the entire video before deciding to make a “informed” comment.
@@RienRocks You mean that thing I already did?
it seems very complex and sensitive to change, and that appears to be the most simple that mechanism can be. as an engineer, my first thought was KISS (Keep It Simple Stupid), and this doesn't seem to be the simplest you could design something like this. it may have it's upsides, but I'll trust that the chain on my bike won't snap, and if anything breaks i can replace it easily, quickly and cheaply, and even on the road. dynema is also notorious for performing poorly when heated, so i would trust it even less on a hot day, or riding particularly hard. you mentioned wide gears as one of chain derailleur systems' downsides, but often people want extremely wide gears, especially for road cycling, where the hills can be very steep, but you also may need to ride fast.
overall, too complex, too proprietary, too weak, too sensitive, not trustworthy, and incompatible with other technologies.
ima stick with my chains :P
Indeed and i think the starting position is not optimal, if i put my foot on it i want it to be in a position where i have a long way to put force into so 2 o clock, then i can use my whole weight for the first stroke, if id use the position in the video(4o clock) id have a lot less acceleration for the start.
And if we watch bike races we see thats how most people start.
2o clock or slightly above the best conversion point at 3 o clock, where gravity helps the most.
I considered buying one of these a couple of years ago, but the narrow gear range was a deal-killer. The high price and weird bespoke frame were also turn-offs. I eventually purchased a belt-drive bike with an 11-speed rear hub which was much cheaper, weighed about the same, and had a better gear-ratio spread.
how much does it cost and where can someone get them?
dyneema breaks pretty fast when exposed to the sun long enough so better drive in the shadow :) really cool invention!
4:41 this is probably the coolest feature
10:49 you don't need different size drums, since the gear setting on each side is independant (and yes they DO need adjustment 1:10)
thanks for sharing!
Thank you so much for the education on string drive. Never heard of this before, but now I wish it had succeeded, and they lasted for 10x longer, and allowed for electrification, too! It all just seems way better than exposed chain; which we've been using for so long now. Surprised to see there aren't even more types of bikes available out there today. AI might soon change that though.
After >150 years, what works well and is practical has pretty much been figured out.
@@gaoxiaen1 Thankfully no engineers think like you.
We wouldn't have cell phones, commercial jets, computers and a million other things that came along after 150 years ago...
@@BitBuhkit So why don't you think of something better than wings for airplanes, or wheels for cars? Get busy Mr. Engineer!
@@gaoxiaen1 lol, I'm not the one that thinks everything stopped >150 years ago!
@@BitBuhkit Me neither. It's just that sometimes the best practical soltions have been worked out long ago. Yes, in some circumstances there are better devices that can be used, but I don't see things like the screw, the nail, the bolt and nut, the table and chair, the metal can and glass or plastic bottle, etc... going away soon. Yes, the string bicycle is an interesting novelty. So is the hubless wheel for motorcycles and turbine engine car and many other inventions, but it takes a long time to replace a tried and true practical solution. Fuel injection (of whatever type) and overhead valves for gasoline engines used to be exotic and futuristic, but have only become commonplace in the last few decades. Most inventions remain only novelties.
It almost feels like you could rehash this tech using standard-ish ebike frames. I don't know if the geometry works, but if you could build a unit that bolts into the space a Bosch ebike motor (or similar) uses, it'd be an interesting idea. One-sided, of course, maybe even something that fits on a HG freehub.
Its amazing how far engineers will go to solve the problems of bicycle chains, hefore they resort to the obvious solution - a chain cover!!!! Honestly, my daughter's bike has an almost entirely enclosed drive train, and i basically never have to clean it. She's ridden it thousands of miles now with no issue. I wish adult bikes came with enclosed drivetrains more often.
Exactly. I've been advocating drivetrain fairings forever. Why do they say a rear derailleur gets dirty but a IGH does not? So helpless. Just cover it up, then it won't get dirty.
Nah, covers are not cool. Have you heard about dork discs? Usefull, light but absolute no-no.
You can use a full chainguard with a single speed bike, or with internal gears, but not with a derailleur. Oh, I suppose someone could design some montrousity that would fit over a derailleur, but I think it would create other problems.
@@thePavuk The only people who want chain guards want to ride with pants, so I don't think they care much for cool.
works well in a sterile environment. a bit of grit and those ropes are gone as well as the polished glide paths
Wow half way into the video these seem like they solve every single issue i have with normal bikes, cant wait for these to be common, unless there is a big catch coming in the second half haha
The design reminds me of the elliptical trainer used in the gym. The device has the option to use leg pedals along with reciprocating handles which resemble the reciprocating motion of the string drive. I often used the elliptical trainer and increased the resistance (compared to higher gear ratio in bikes) by holding the handles closer to the hub, i.e. lower. In my opinion something similar can be used for hand bikes (used by people with lower body paralysis, who cannot pedal). Reciprocating handles would make full use of the simplicity of the string drive because no spinning pedals are required. The hand-cyclist can adjust the gear ratio simply by changing his hands position: Low gear is achieved by holding the top part of the handle. Holding lower can increase the gear ratio.
would like to see the resulting physical development in heavy users at their peaks.
Some time about 1974-1976 one of the bicycle magazines in the US had an article on a cable drive bike. What is shown in this vid looks very familiar to my memory from five decades ago.
Sounds really cool, but all the proprietary compenents sounds like the opposite of what you want in an easily repairable bike
I think they went with string for two reasons: 1) It's not going to wear the other surfaces, it'll wear out first, and 2) It's not particularly dangerous if it snaps. This could certainly be designed with other materials, but you'd either end up with immense wear and tear on other parts, or danger if it did snap under tension. I feel like they could have probably made these far more robust though in a few ways, like for example, having a metal spring core in the strings, while also making the string thicker. I could imagine for example, a string in the center, wrapped with a metal spring, and then an outer rubbery layer added or something like that, giving it a lot of flexibility and durability.
this low key just seems like an ad
Yeah he should have shown family guy clips on the side or something
@@s.a.j.7116real!!! this fool is not really with the times imo...idk
You never explain how it works. :(
Just look at it dude. Pretty simple if you put some thought into it
It pulls the strings which pulls the rope and propelled the wheels
4:30 not true for a lot of internal gear hubs, with most of them you're not supposed to or just cannot shift under load and you only can while stationary. So the string drive definitely has an advantage there. As for an ebike string drive, why not just put the electric motor on the front hub?
I wonder if some kind of coated wire would work better than the strings? As far as using disc brakes on the back wheel, a solution would be to build it around the wheel hub -- inside the spokes -- with a wireless control that could clamp on it for braking.
A comparison would be great on efficiency. Is there a leg electric drive ?
I use dyneema rope on my atv winch. It works great and, like he said, it floats. That’s nice when tossing across some water and the hook doesn’t quite make it to shore.
I'm curious about the efficiency of this. Since it goes against a simple principle of reducing parts (under the assumption that the bike chain is "1 part"). Now we have 2 drive chains, cams, pulleys and winches. Basically more than doubling the amount of bearings, and while strings are way more smooth and efficient in transferring energy than a chain. Having a reciprocating winch and cam system seems to add a lot of friction to the system. Especially the winches, which have to coast 50% of the time.
Seeing the shaft torque to wheel torque compared between belts chains and strings (or any other system) would be extremely interesting.
I like how it couldve changed the bike industry. Unfortunately we cant find this option but i appreciate continuous effort of scientists and engineers and designers to constantly reinvent things so we have better and various options. Thank you for geeat video
Noticed that only regular bikes have gear adjustment cables between seat tube and rear wheel, forcing for longer wheelbase. Those performance bikes have been set up other way to pull gearing cables.
*Summary*
* *00:00:37** String Drive Basics:* Bikes with a drivetrain using Dyneema ropes instead of a chain, produced from 2011-2021.
* *00:01:54** How it Works:* Pedaling moves lever arms that pull ropes attached to the rear wheel, winding and unwinding on drums.
* *00:00:58** Key Features:*
* *00:00:58* Grease and oil-free
* *00:01:04* 19 gears
* *00:01:04* Shifting while stationary
* *00:01:11* No gear adjustments needed
* *00:02:19* Ropes are stronger than chains
* *00:03:46** Advantages:*
* *00:03:46* Smooth and silent operation
* *00:03:52* Virtually no maintenance
* *00:04:23* No derailleur to damage
* *00:04:42* Automatic favorable pedal starting position
* *00:04:54* Only consumable is the rope (cheap and easy to replace)
* *00:05:15* Minimizes "crank dead spot" for potentially better efficiency
* *00:05:39* Easy rear wheel removal
* *00:06:05* Closely spaced gear ratios
* *00:06:36** Disadvantages:*
* *00:06:36* Requires a special frame
* *00:06:56* Proprietary components
* *00:07:09* Incompatible with disc brakes and e-bikes
* *00:07:43* Shorter rope lifespan than chains or belts (1000-2000 km)
* *00:08:08* Grip shifter can be stiff and doesn't integrate well with drop bars
* *00:08:28* Heavier than derailleur systems (~1 kg more)
* *00:08:35* Potentially less efficient than chain drive
* *00:09:17* Smaller gear range than modern drivetrains
* *00:10:32** Quirks:*
* *00:10:32* Can pedal backwards to move forward
* *00:10:44* Allows different gear ratios for each leg
* *00:10:56* Reduced "crank dead spot" effect (like oval chainrings)
* *00:09:46** Why it Failed:* Ultimately, the proprietary nature, incompatibility with emerging technologies (disc brakes & e-bikes), and the rise of strong alternative drive systems (belts, internal gear hubs) led to its demise.
*In essence, String Drive was an innovative, clean, and low-maintenance drivetrain solution that was unfortunately hampered by its proprietary design and the timing of its release, coinciding with the rise of other competitive technologies in the cycling industry.*
I used Google Gemini 1.5 Pro exp 0801 to summarize the transcript.
Cost (if I didn't use the free tier): $0.0421
Time: 34.47 seconds
Input tokens: 8602
Output tokens: 1142
Absolutely, the cashback saved me last week. It’s a good feeling to get something back after a loss
That was an interesting description. I might mention though that every problem listed can be fixed. This includes:
Adaptation to existing bike frames.
Wider gear ratio.
Compatibility with disk brake.
Greater wear life for cord.
Lever based or automatic rather than twist grip shifter.
Wider gear ratio? What makes you think that? This thing has 19 speeds, my shitty mountain bike has 21.
@@iamfreeareyou681
I have no idea what point you are trying to make or how it would relate to my post.
the wider gear ratio as in the range from the highest gear to the lowest not how many gears i would also like to mention that disc brakes are not nessary in the rear because of wheight transfer when you brake and rim brakes are more than cabible of locking up the rear tire but disc brakes are nessary for the front but they can install them anyways since there is noting preventing them.. note i do know that there are other benifits to disc brakes for example not chewing through wheels longer brake pad life as well as better distribution of heat but if you are using your rear brakes enough to where thats a concern there are different issues
@@3-ro3cd
> the wider gear ratio as in the range from the highest gear to the lowest
Yes, you agree.
> disc brakes are not nessary in the rear
And?
Have you looked at the reload bonuses They seem perfect for keeping the game going after the initial play
Fun video, and fun concept! It seems like the pedal parts rubbing against the inside of that shape would cause significant issues, especially if any dust got in there, which it instantly would. Didn't hear that mentioned in the video for some reason ...
Very close gear ratios require frequent shifts.
I found that large gear gap help us pedal more efficiently across a broad rmp range.
Single speed racers often outperform cyclists with gears, especially on section with speed fluctuations, where you'd think you need the gears the most. I've found it ideal to have few gears, and use each for a "scenario". One tailwind or the road, or a fast downhill, maybe sprints. Two for spirited flat road or offroad flat racing. Three for undulating low elevation change, winding singletrack. Four for climbs too long to sprint up in 3rd. Five for really long climbs or very technical climbs. Six would be for hour-long super steep off-road clibs, or low effort road climbs. You'd hardly ever shift. Our legs can handle walking and sprinting, they'll be fine.
The efficiency of a rotary engine can exceed 45%. The efficiency of the piston engine is 30% in an ideal design. Circular motion is much more effective than reciprocating motion.
Maybe you could also suggest replacing the metal bearings with wooden bushings with tar?
I'd suggest that the best starting position is not with the pedal in the horizontal position, but higher than that.
Fascinating. The persistence of chain drives after 150 years lies in the surprisingly low overall frictional losses, especially with the refinement of chains themselves, optimized cogs, and good old wax as the basis for the best, easily maintained lubricant. Motorcycles with drive shafts have far higher frictional losses, only offset by sealed systems, and the power to spare from an engine other than a human. This design also has many more pivoting bearings, likely needing service or replacement.
I would love to try it. I’ve broken chains on sheer force alone. And to put that kind of strain on this would be fun. Even if it didn’t fail.
The concept looks interesting at first glance, but overall it doesn't convince me. too wide, too many parts in the bottom bracket area and just as susceptible to dirt as chains. ... well.
chain drive is more efficient. Ropes stretch when torque is applied thus using part of the energy for stretching the rope and not for propulsion. Some motorcycles use a kevlar rubber belt which is stiffer than rope.
This is for what? For drive in a park on a weekends?
Everyone constantly forgets that a bicycle is not only a ride in a straight line. How will this work for example in the forest? Among the pits and roots? This is a 'one of' example.
Did you notice the cashback offers? It's nice to know there's a fallback if things don’t go well
I think they needed the extra tensile strength, because the force on the string is way higher than with a chain because it just pulls half of the time but then with double the force i think.
It would be worth testing here in Bavaria in winter, (where many of us continue to bike to work even in the snow with the appropriate winter tyres or simply with the MTB). From the point of view of pedalling efficiency it is one of the solutions to avoid pedalling deadlocks (in France a century ago a two-way pedalling system with two chains with two sets of different ratios was also tried out) but I would have doubts about long-term reliability and daily use on all kinds of road surfaces and different climatic situations. Especially for dirt and foreign bodies that can interfere with such a system.
The linkage and cable drive system is ingenious (although there are analogies in applications on industrial machines) but I find it complicated to manage in terms of reliability and maintenance
Though this drive train is maybe not the best for bicycles it would probably be very well suited in therapeutics as a stationary bike that offers different levels of difficulty for each leg. Allowing a weaker leg the ability to train up to the stronger leg (and maybe make both legs stronger).
String spokes on both Olympic Gold medal winners XC bikes brought me here. I was wondering how long those spokes last?
I was also wondering if strings could be adapted somehow to a deraileur with pulley wheels and pulleys instead of a chain driven cassette?
Nobody want to change a drive device after only 1,000 miles. Easier is what most people like, hence the internal gear devices.
Good luck driving that in Finland ;)
Besides the dirt problem the 3:20 this would mean I would have to replace them more than 1 time per year compared to almost never with a chain.