@@LewisBuchanan - did you get the trek recall notice about the chain guide having a 5mm spacer installed instead of the required 7mm spacer ?? Seems to have cured the issues. Would be interested to know your thoughts on the bike after the fix 👍 (assuming you can rescue the bike from the skip)
It's because this small, top cog is too much front of the bike and the chainring has worse contact with chain. Compare high pivot in new Slash with Session. It's a design flaw.
Have you tried what Pinkbike said? Pinkbike writes this in their review: After reaching out to Trek and MRP, it became clear that the guide had been improperly installed from factory, with 5mm instead of the intended 7mm of spacers between the frame and the guide. 2mm didn't seem like it would make much difference to me, but after changing the spacing and taking the bike to Pemberton for a huge weekend of riding, I was unable to get the chain to drop again. The trails up there are rough, fast, and full of good chain-challenging moments, so it's possible things are fixed for good.
Well that means that marketing is a thing and real life is another. I have been concerned about all those high pivot trending, at least for Enduro bikes. This shows that they have their use, but not for every use. Thanks for a clear review 🤘🏻
@@fabriciofracchia6732 I own a Cannondale Jekyll and have never had an issue with the chain, stays on great. The only issue I have had is a linkage bolt popping out, but that was my fault as I probably should check them more lol!
This is great content Lewis. Honest reviews are appreciated and I hope you will have a resolution soon. In the meantime, you can reminisce about Balfa BB7 frame design and how well it worked. That and the ancillotti were the best frames I’ve ever had. They don’t make ‘em like they used to :)
The problem with an issue like that for the average Joe is they are at the mercy of the shop they bought it from and in my experience they can often give you a million reasons for not properly sorting the bike, you could be left with an expensive lemon.
Hopefully trek will sort it out, seems to be they could greatly improve it by making the idlers better. Hp bikes drop chains a lot anyways and not too many people seem to complain so I think most people will be ok.
Facts, I recently bought a high pivot bike (I won't name the brand or bike yet until their customer service gets back with me) and the finish is atrocious. On the surface, it's a beautiful bike, but the brake hose routing through the rear triangle has a sharp bend in the tubing (it has an internal tube to guide the hose through the seatstay). It also is rough and may abrade the brake hose. The head tube was faced so thoroughly that the headset compression ring dust cap doesn't cover the facing (so you see raw scraped carbon around the top of the headset). They also did not pack the bike with everything (wrong tire, I received a 27.5 tire for a 29er bike and no PowerLink for the SRAM t-type chain). Now, as a shop employee, I know that we'd build that bike up, get a tire that fits and order a t-type power link, and do what it takes to route the brake hose. We'd sell the bike as is. The customer would always have trouble with the rear brakes, I have no doubt in my mind. As it stands, I have no clue what I would do if the manufacturer doesn't warranty this faulty frame. I guess I would sell it and let the buyer know what they're getting, and name and shame the bike man. Still, the shop is the ultimate arbiter and they aren't always looking out for the end user's best interest. I doubt many shops would send the bike back, in my case.
Coming from a bike mechanic of over 15 years, the only thing I can see from your slow-mo video is slack chain between the top idler and the chainring. This could only be caused by a sticky freehub putting forward rotation on the chain, otherwise the freehub should always spin back taking up any slack on the top side of the chain. This could also be caused by the chain jumping on the cassette and causing it to "jam", pulling on the derailleur and then putting slack chain on the top. I would try a different rear wheel before blaming the bike, but it could also just be the bike ;)
Sounds smart and what is actually about changing all the parts of the drivetrain ? You could take the same line of parts but just new ones...could also just be that one tooth, one chainring what ever is maybe weird produced
Hi, I dropped into the comments to say something similar. Watching it at 0.25 speed you can see on the 1st chain drop the slack appear between the cassette and the idler that then whips round the chain and throws it off. Based on that I would say that it's a freehub or the bearing in the idler that's to blame.
@@jimthesa1ntyou both close but the issue is actually from the rebound of the bike, when he compresses off the lip his chain length increases, then as he unweights the bike with a fast rebound the chain is left to become loose in free space as the cassette and front sprocket distance decreases rapidly, leaving the whole chain to become weightless and floating off. Only solution here is a idler pully with a fast acting tensioner to remove the slack during the rapid change from rapid decrease is chain growth! The tensioner would have to be very responsive tho!
So I have been riding the Forbidden Dreadnought for 2 years and switched back from the old gx AXS to a shimano drivetrain. My collegues on bikes with "normal" suspension designs never had issues with AXS. For me it seems that the clutch on at least the old AXS is just too weak and cannot be adjusted at all. I did have a couple of chain drops (I am not using an idler behind the chainring) on rougher stuff but never again with the adjustable clutch on the shimano derailleur. The bike was loud as hell as well because of the AXS derailleur moving around so much and the chain slapping. I am not sure if the transmission is the same though. On your slow-motion footage it almost looks like it. If you play back the drop footage really really slow with youtubes 0.25x speed you can clearly see that the derailleur stays up top for after the initial impact and thats seems to cause the loose chain to come of after the following chunk. Before that right after dropping off the slab when the rear is rebounding and getting shorter (as on pretty much all HPP bikes) the loose part of the chain seems to wander forward beyond the idler on top. Before the impact on the floor the chain is already pretty loose between the idler and the chain ring. If you ask me, I'd try out a drivetrain with a stronger adjustable clutch for chain tension.
btw you can go through videos on youtube frame by frame with , and . After looking at the footage im 100% sure that, like you said that the chain cant go back fast enough when rotating the crank backwards wether its due to to the top pulley positon or too much friction in the drivetrain. You can clearly see the chain links making a little "v" on the chainring already in the air, and then the impact on the ground + the loose chain around the chainring makes the chain come off.
Clutch on the derailleur is likely not stiff enough. My axs had zero chain offs until a few weeks ago, now it happens occasionally. Checked the rear mech and it there was little resistance compared to a friend's brand new (also replacement due to bad clutch) derailleur
I added T type and MRP to my dreadnought a few months back. It’s mullet with ziggy so almost identical in appearance to the trek. I have smashed it at dyfi week in and week out and had no issues at all with the drivetrain. What you have experienced absolutely should not be happening. Hopefully trek can sort this for you as there is clearly some design issue that’s been overlooked somewhere. Great content, fingers crossed for you as 5k is a lot of time and effort to go down the drain.
Could it be bad/sticky bearings on the freehub body? That would basically cause the chain to have more tension at the bottom and possibly slacken at the top. Add the high-pivot+idler design which shortens the axle-idler distance as the suspension compresses, further exacerbating the low tension and slack at the top, that's basically your recipe for a dropped chain.
IIRC from some of the tech talks I've seen on this bike, Trek has designed the rear suspension with the lower idler to intentionally limit an increase of chain tension throughout the travel (similar to how the upper idler eliminates pedal kickback, the lower idler prevents lower chain tension from imparting forces on the suspension system via the derailleur cage). They showed clips of them cycling the suspension through the travel and the derailleur cage did not move. I'm sure a big brand like Trek has tested the hell out of the bike, but maybe an increase of chain tension as the suspension compresses would keep the chain on better?
Its common knowledge chains come off from side to side movement, basically the wide link of a chain will hook on the top of a chainring tooth and derail itself. The top pulley on the Trek doesnt have narrow wide teeth to stop this, the teeth are also very shallow, the lower idler is even worse. Having mega tight clutch tension would help, if it was adjustable, but basically the design is just flawed. Running two chainrings with narrow wide teeth can cause issues if the chain skips, but it should never skip like that - the top pulley needs to have a fully wrapped around guide if using standard teeth. The bottom guide needs to be ditched or again use a much taller guide to stop the chain jumping off - one look at the Commencal V5 will show you whats necessary to overcome the issue.
Hey Lewis, I don't know if you'll see this but pinkbike had problems with it in their huck to flat field test. They realigned the lower pulley wheel by 2mm and apparently solved all the problems.
My buddy just got the new slash and had been riding the hell out of it. He’s like 275 pounds and this bike has been an absolute tank for him. No drivetrain issues yet
Is the top idler pulley narrow/wide? I have a Norco Shore 2 and had similar issues with the chain always coming off. I concluded it was because the idler pulley wasn’t narrow/wide. Bought the Forbidden idler and haven’t had my chain come off since.
I've called Trek out on a couple of frame design issues in the past, they sent out replacement bikes both times.... Same issue, both customers got refunds and bought a different brand of bike 💁🏻♂️
As a bikeshop mechanic for more than 10 years - when you buy a bike from a shop the mechanics at that shop will have removed the bike from the box and fully checked the bike is built correctly and the gears and brakes are functioning as they should. After a break-in period the shop will usually offer a “free first service” to dial in anything that might be wrong (like indexing adjustment). If the bike has come from Trek’s overseas manufacturing facility straight to you in a box then anything might be wrong with it. Typically these are thrown together as quickly as possible with little to no grease and shipped to distribution centers to be correctly assembled by the bike shop that is selling it. This does not seem to be incorrectly assembled - this seems like a completely flawed design that will never work…
There are 2 types of boxed new bikes, manufacturer to dealer, that works as you've described, and manufacturer direct to consumer, like YT, Canyon, Trek, etc. Lewis is right in that the bike should be ready to ride out of the box, BUT I think that it's still a good idea to have direct to consumer bikes checked out by a mechanic. Nevertheless his issue seems like it may be a design flaw. High pivot mania is adding so much complexity to mountain bikes for so little advantage. World cup downhill and enduro races are still being won just fine on traditional linkages where any real advantage would show itself in such slim margins.
I worked for a Trek dealer in the UK - I was unaware they had moved to a DTC model - where I live now, in the USA they have done the opposite (they are buying the local shops and rebranding them as Trek shops). When I left the UK the only real DTC brand was Canyon - and every one of those we unboxed we would charge £150 to put together and they were terrible…
I struggle to imagine that a flaw this large would make it through Trek RnD (totally possible but seems unlikely). The only thing I can think of is that you are unlucky and have copped a dud frame with sections of the tubing out of tolerance. I would personally pull the frame apart, and when rebuilding it, check that all bolts line up correctly and go in easily. If there is any fighting required you know they didn't have it in the jig right when welding or something. Definitely a major PITA
I got to demo the Slash 9.8 AXS the day it was launched. Rode some of the roughest stuff in the Lake District and had no issues with the drive train. I even tried to shift gears as badly as I could - under load and in quick succession - the T-Type was flawless. Bike road great. That being said...my take-away was I wouldn't buy one 'cause I'm rubbish at mechanics and there's just so much going on with the drive train I'd be stressed out about cleaning and servicing it.
Trek store mechanic here, the only thing that I can think of is the eye to eye size of the new shock you installed. Is it identical to the stock shock? If not this could affect the rear axle path during compression. Also I would recommend checking the freehub body, if it doesn't spin freely it can cause the chain to bunch up between idlers when you stop pedaling suddenly. Best of luck.
That’s super weird! I have the exact same bike and size. (I sized down to ml for a more playful bike as well) I’ve done trails way more chunky than these trails shown and I’ve never had my chain fall off…
If you pause it on the drop the chain is already off before you land. Something is making the chain slack around the chainring. Other people have the said the mech, could also be the chain is a bit damaged or has a sticky link, and maybe the top guide is catching on the chain.
I went frame by frame at 5:25 and the chain between the chainring and the top idler wasn't tight for the whole video clip. I suspect that the derailer can't put enough tension on the chain to overcome the drag in the free hub. Have you checked how much tension your derailer has vs other derailers? Maybe you got one with a weak spring or maybe that model just has a weaker spring than others.
Since these derailleurs don’t have B tension getting the rotation of the derailleurs correct and torqued correctly is imperative. Being slightly off or not tight enough so it rotates messes the whole system up. A high pivot bike with all that CS growth could be pulling the derailleur forward over repeated hits and putting it out of adjustment.
I think it very well could be the clutch in the derailleur. I don’t think it’s allowing the correct amount of tension which is allowing play in the chain and allowing it to come off under bumps. I think a potential quick and easy thing to do would be installing a different transmission derailleur from a friend or a bike shop demo bike and give that a try.
Great to see honest reviews, there are so many industry plants with so many biases pushing new parts and bikes onto consumers, mountain biking is fucking terrible for it at the moment. These reviews are a breath of fresh air mate. Cheers!
slowmo on the drop if you go through it frame by frame you can see what the issue is. There is excess chain between the chainring and the idler when in the air. As soon as the rear wheel hits the ground that goes slack and comes off.
At 5:28, look at the bit of chain between the high idler and the chainring. It's NOT a straight line. As if the cassette rotated slightly in the drive direction forward when the suspension unloaded, pushing the chain towards the high idler (but your chainring was stationary when going off the jump), and that introduced slack inbetween the high idler and the chainring. It's very obvious. When you landed, that slack was still present, and the chain merely stepped off the idler from the impact alone. Trek almost needs to add yet another tensioner between the high idler and the chainring to prevent a backpedal induced chain jump-off
Noticed the same thing, and I think there's an issue with a tight upper pulley or maybe free-hub, chain getting stuck somewhere in the derailleur, or simply weak chain tension. Lewis should to backpedal sharply and try to find what could cause this. Nothing what a competent bike mechanic couldn't solve.
Damn, good eye. It's like the hub isn't freewheeling properly and is pushing the chain forward but it has nowhere to go because the cranks aren't moving.
@@krushiXX Yup, you nailed it. The free-hub has more drag than the idler. The chain is being pushed forward by the cassette, rotating the idler, which gathers the chain up at the stationary chainring, creating enough slack to pop the chain off. I'd try a different rear wheel.
My bike used to lose the chain in the same way as well. Turned out it was a worn chainring and the tension in the derailleur was very weak. I now run shimano and NEVER have a problem becasue there’s an actual clutch
And what should the firm Trek do now? The bike is on sale! Not very good support Track ! I generally dealt with a crack in the frame Slash 5 but was not the first buyer, when they found out it, they stopped responding !
Man I’d look into a Santa Cruz nomad. They have an ever so slightly rearward axle path. Just went to one from a RM Slayer. With it now being mullet it would tick all your boxes and not have any ridiculous drivetrain nonsense going on.
The SRAM tech paper for frame builders says UDH (Universal Derailleur Hanger) is not for high pivot idlers. It says the chain needs to be horizontal. Trek neglected to read this apparently.
idk... i'd try 32 tooth chainring for a little more contact w the chain and double check narrow/wide teeth line-up correctly with the chain? I ride the Forbidden Dreadnought high pivot with Cascade's chain guard/retention and Forbidden's Race guide, and have had no problems like this whatsoever. hope this gets figured out for you
Hi, My name is Devin Armstrong I am 15 years of age and live and ride in Whangārei, New Zealand. I really think you should try out a gearbox bike if you’re still looking around. I would recommend one from either zerode a company out of New Zealand designing and testing the bikes in Rotorua. Cavalarie a French company using the less common effigear gearbox or viral bikes with their new optimist 160. The chain or belt depending on which company you go with should be impossible to ever drop as the bikes are all technically single speed on the outside. Effigears gearboxes are unable to shift under load however the pinion gearboxes found on the other two bikes can. The optimist 160 is not yet released but is specked with pinions new smartshift gearbox Sean on the gamux dh prototype. Zerode has not yet publicly announced the use of these gearboxes however I have had a chat with them and they expect to be using them in January next year. The suspension performance on all these bikes is next level thanks to the weight of 12 gears, a derailleur and heavy chain being deleted from the back wheel making small bump sensitivity insane as shown in a drop test on zerode’s UA-cam channel. Personally I would recommend a zerode as they have been around for many years and the optimist is viral’s first full sus bike. I think everyone’s riding can be drastically improved on a gearbox driven bike and have recently started a job to save up for a zerode katipō and think gearboxes are the future of cycling especially with pinion’s new technology.
i was thinking of replacing my 2017 giant anthem, but i guess i hold on to it a little bit longer. it has never dropped a chain in the 7 years that i owned it.
Trek has gone downhill the last few years in my opinion.. many friends have had broken frames..wheels etc. That’s a nightmare having problems with a brand new bike!!!
Could you put the bike on a stand, unbolt the shock at one end and then see how the chain moves as you lift the rear wheel up and down through the travel with the chainring held static. That would replicate what happened on that big landing. Would be interesting to see if big amounts of slack are introduced between top idler and chainring.
Lewis uploaded another video introducing the bike a couple weeks ago and included a demo video from Trek that showcase the chain movement / pivot like you've described, was pretty interesting
@@AJR-gg just watched the Trek vid. It doesn’t address what happens to the chain between the top idler and the chainring. I think there would be value in disconnecting the shock to do an experiment. Also what happens if the pedal rotates slightly fwd or back during the jump - does mech. Front wheel spinning fwds too so that cassette can’t rotate back. 🥼🥽👨🏻🔬
have you tried a new derailleur? The slash's idler is on the arm and not the pivot meaning the location of the idler moves, basically acting like a weak clutch between the chainring and idler. I believe they had similar issues on the session and why we seen prototype arms on that bike a few times.
When people have the chain coming off and down the cassette while backpedaling its usually the brand of the chain. Do all spec versions run the same chain? Are both idler pulleys narrow wide? It definitely sounds like the chain is rolling off the pulleys because chain growth is eliminated that means chain tension is much much less under compression. Believe it or not I think the mech clutch is not allowing the chain to maintain tension
Bikes may come assembled but that does not mean we shouldnt go over the whole bike in detail and re torque everything to the proper specifications. I like to think of a box build as a "shape forming" and it is up to the shop and the rider to double down and check it again.
one other thing from the Slash service videos..... they say the "lower shock mount and shock need to be torqued to spec with the Bike OUT of the stand and on the floor, this allows the shock and mount to centre itself under the weight of the bike". Not sure if this would make any difference to the issues you've been having but thought I'd mention it anyway.
Before you bin in. TRY THESE: Change the chain to an XX1 T-Type. Upgrade to an aftermarket Chainring. To me, its like the chain itself is too wide/not engaging in the chainring teeth. You don't see this sort of thing on Eagle or Hyperglide II chains.
If you can find an older SRAM derailleur try it with that. I've noticed the clutch in newer SRAM derailleurs aren't as taught as they used to be so the chain is just too sloppy.
I think pivot has don't high pivot right on the test bikes using 2 chains like it's alot more complex but remove pretty much also issues of having such a big chain
Weird to me that the bottom pully can’t be moved closer to the chain ring like back with old E13 chain guides. For the top, the guide should cover more of the pully wheel for when we pedal backwards granted chain line should fix that. But I won’t touch one of these at my shop for another few years.
I ride the Session HP since a while now and had issues with the derailleur clutch not providing enough tension. Changed the deraileur and problem was solved. Maybe try a different rear mech as others also mentioned.
Hope trek reach out and explain this…I have a trek fuel ex 8 from 2017. Things a dream. But far simpler than the slash. Ain’t broken….don’t fix it. It’s like they enjoy reinventing the wheel.
As the suspension compresses the chain is becoming too loose, this is probably because the rear mech can’t put enough tension around a chainring and two idlers, when the rear mech is in a more vertical position the chain will be pulled in a steeper angle compared to the bottom idler, this it’s when it will probably be jumping off the top, and when the rear mech is more horizontal, like when on the 10 or 11 tooth there will be more slack in the bottom and that’s why it’s jumping off the lower idler. The riders trek used in testing maybe don’t race enduro , trek should have made sure that the components were compatible with there design. Bike design looks to complicated, and heavy. Keep it simple and easy is best
I think the problem is the flattop chain from the transmission because my homie have also a slash with a shimano drivetrain and his chain never felt off
40 pounds ! What a tank I'm still riding a 2020 slash 9.9 sram eagke gold, lyrik ultimate, roch shox super deluxe shock, xt 4 piston.brakes, renthal cockpit , dt swiss 240 hubs 511 rims, minion dhf exc+ with cushcores. Bike weighs 30.5 pounds. Pedals very efficiently and rails downhill Chunk etc. Every new bike I test rides very inefficient feels like the brakes are dragging .
Bought a Trek Stache a few years ago. After three replacement frames it was determined that the chain rubbing against the stay was a design error. Didn’t work with SRAM 1x. You have to wonder about Trek’s R&D. I’d never buy anything else from this brand.
A few things that fucked with my dreadnought: broken hub axel. Derailleur loose. Also, is it possible your rear triangle was hit in shipping? Alloy bend.
If you use the app to calculate the chain length it does say it’s compatible with chain rings 2 sizes bigger. Maybe test the app with a 28 tooth and see what it spits out for chain length I’m guessing it could be shortened or toss on a bigger chain ring for a test lap. Either way super annoying and shouldn’t be an issue on a 6-13k bike at all.
Finally an honest rider! 👏 ❤ Idlers cause unwanted tension in the chain and they break constantly. Single speed for the win. Canyon Torque does the same thing with no idlers at all.
I bought a new, very expensive bike this last January from a very reputable brand and the derailleur bolt kept coming loose, no matter how well setup it was. I even replaced the bolt with the top of the line version and the problem persisted. Ended up replacing the whole transmission for a different brand and it has been working flawlessly for months. Rumor has it that the OEM components were not completely compatible with this specific frame, but they specced it on it anyway... This made me mad, such a lack of care on bikes that cost more than a small new car...
Okay... I've decided to 'jump in' to this situation... I have a few thoughts(forgive my ignorance as the case may be): 1. Weather it's side to side, or top to bottom - there is too much play behind\above that top chain guide & pulley... & the proof regarding that(even though I haven't seen the bike\drivetrain in person), comes from the FACT that in order for the chain to come off, said chain MUST rise UP off of the guide pulley(so weather you glue rubber or plastic on or adjust the guide - reduce the space above the guide pulley)which 2. It doesn't seem as if said guide pulley is of a narrow\wide nature which should further reduce drops(as I'm certain you know by now)... Anyways 3. I had the same thought that you mentioned regarding reducing chain length - but since you said it's in order, how about something being wrong with the clutch or general tension of the derailleur? 🤔
Check hub to make sure it’s not binding in any way. Check derailleur make sure the clutch actually has resistance. You’d think sram would make sure that every T type drivetrain is 100% perfect but now days I doubt that. I see just as much warranty issues from high end components as I do low end components. You’d think trek would have that dialed in or at least have a inside tech that could help diagnose it. I get the frustrations tho.
I think the gx trasmition isnt desinged for 2 idlers, because its a lot harder to pull the chain with to more idlers. You could try it without the lower idler like most other high pivot bikes do.
You need both idlers because otherwise there is almost no chain wrap on the front chainring. Its the same reason why the original druid had a guide at the bottom. On the druid v2 forbidden moved the top idler back so that there was naturally more wrap so they could ditch the lower guide. Kinda crazy that Trek didn't have this problem in all their testing.
also I had a similar problem with an older bike, I think a much shorter chain, and much less lower guide tension would do the job, on the lower side, the chain should be almost horizontal, just a bit of pullup on the chain, and maybe move the lower guide closer to the chainring if possible, that decreases the tension on the derailleur, if the springs in it are less stretched, the derailleur can much better actuate. you can confirm the latter with switching over to a saint derailleur for example, because they have bull strength springs, that can somewhat work with very bad chain tension. if it doesn't occur with a saint, it's probably about chain tension, and apply stuff I mentioned above(hopefully)
I've designed a high pivot bike, you need to have the lower idler as high as possible to have the lower chainline as lose to passing thru the pivot. This reduces the amount of "stretch" thru the travel. Then set chain as short as possible.
think this could be from the idler moving away from the chainring in compression? if its not happening all the time, could be a function of that and shock speed...?
I agree with what someone said here about the clutch being weak having seen in that slow mo just how slack the chain is getting but unlikely that, maybe just nature of those new derailleurs. However, totally agree that the upr idler guide should be further forward OR if you look at Yeti’s proto DH bike have a guide similar to that over the upr idler. They may have had a similar issue and made that to fix it
@@kingflynxi9420 are they adjustable for the chain length? I thought only for how hard it was for it to ‘break away’. Chain length shouldn’t matter as, if the chain is the correct length, won’t affect the angle/position of the derailleur in each gear and will always be the same regardless of length.
Completely right in your analysis. If it is a bicycle to take it to its maximum and that an anchoring system does not work, nor buy it Greetings and it was an expensive investment
I`m on a high pivot bike myself (deviate claymore) and the chain didnt come of once. The bike is overall realy good and i only can recomend it, if you want to try out another highpivot bike.
Have you checked if the cage on the derailleur is straight? A mate also has the new gx transmission and his shifting was garbage and the chain came of all the time after he hit the cage slightly. We replaced the cage and its working good now.
The problem is Trek’s high pivot design. Due to the location of their idler, being too forward, it is causing your to chain drop. A larger chain ring could solve your problem
If the free hub body is not working properly that could happen, maybe you could check it out and make sure that as soon as you stop pedaling the cassette stops right away if it doesn’t then it would push the chain forward and will make it go off. I watch minute 5:28 at x .25 an zoomed it, before you land i noticed that the chain looks weird, is seems like there is no tensión from the high pivot to the chainring that why I suspect of that. Industry nine is easy to open, it only has a plastic seal and you just pull it and get it out.well is that same seal the one that if it doesn’t saddles well gives problems
I wonder if its a frame flex issue? Trek have probably tested this setup to death with a carbon frame but I wonder if an aluminium frame is just produced without any real testing to offer a cheaper alternative? we all know carbon frames are stiffer, so maybe it is frame flex that's causing it.
It’s like the age old saying, If ain’t broke don’t fix it 🤷🏼♂️ companies always trying to reinvent the wheel and it always just causes more headaches and potential failures and problems.
Well if you want a testimony for the spindrift, everyone I've watched on youtube loves theirs, and the guy I ride with has one. It feels very capable and hasnt had a single issue
my mate has a gen 6 slash but the base model with shimano. he hasnt had issues with the drivetrain but it seems all ttype models have issues for the fact that ttype doesnt really have a b-tension
Its surprisingly common in the industry for bikes to need assembly and tweaking out the box by a qualified mechanic. Even the legal classification of a 'true' wheel for sale is quite wide and ive had to adjust spokes out of the box, bleed brakes, add spacers and trim chains. That being said these problems on your bike are inexcusable and quite baffling, im leaning towards a design flaw somewhere since you checked so many different parameters.
The top Idler Ideally needs to be narrow wide that will stop it dropping off the top. As for the bottom one it looks like it could do with being closer to the chainring, is it possible to adjust this? I have a GT force that is very similar (hight pivot with idler) and have no problems with the chain coming off. On the GT the top idler wheel is narrow wide and I have set the chain guide up so it is very close to the chainring.
Since the drivetrain uses both sides of the chain, I wonder the new Sram chain may be an issue because it is smooth on top and shaped differently. Trying an old style Sram chain or Shimano drivetrain might make a difference, I don't know. That Sram chain is just released new tech, maybe during testing, Trek only used older style chains. Just a thought 🤔
If you pause the video at 5:28...you can see the chain is off before the bike had landed so chain started to come off on way into the feature. Angle isn't lined uo earlier to see what has happened
the recent article on Pink bikes gives you an indirect nod..... here' the fix.... incase you didnt read it already. MRP MXg Chain Guide: This innocuous seeming lower roller may have proven to be the most controversial element of the new Trek, given the issues quite a few early users had with the chain dropping off the roller during fairly normal riding scenarios. I had this happen quite a few times during testing, both in the bike park and on lower speed tech trails in the area - all to some frustration. After reaching out to Trek and MRP, it became clear that the guide had been improperly installed from factory, with 5mm instead of the intended 7mm of spacers between the frame and the guide. 2mm didn't seem like it would make much difference to me, but after changing the spacing and taking the bike to Pemberton for a huge weekend of riding, I was unable to get the chain to drop again. The trails up there are rough, fast, and full of good chain-challenging moments, so it's possible things are fixed for good.
Your chain was off before you even landed the drop. Something is faulty or damaged. Bummer, me and two buddies have this bike, we love it and have had no issues other than with some of the SRAM stuff.
Interesting that @5:26 you can actually see the chain bunch up between the idler and chainring as the suspension comes to full extension, quite a visible kink in the chain. As you come past the camera you can see where one of the links is already popping off the narrow wide chainring and that's the one that gets thrown as you land and compress the suspension.
I saw people commenting about the new derailleur is not build for this kind of bike, what if throw in a cable actuated derailleur and see if it will fix the issue. May it be sram or shimano
My mate has the same bike and dropped the chain on nearly every run at Dyfi bike park.
Yup… tht sucks
@@LewisBuchanan - did you get the trek recall notice about the chain guide having a 5mm spacer installed instead of the required 7mm spacer ?? Seems to have cured the issues. Would be interested to know your thoughts on the bike after the fix 👍 (assuming you can rescue the bike from the skip)
Mate has one and rides it like he's possessed, not drops. Runs mechanical Shimano.
It's because this small, top cog is too much front of the bike and the chainring has worse contact with chain. Compare high pivot in new Slash with Session. It's a design flaw.
Have you tried what Pinkbike said?
Pinkbike writes this in their review:
After reaching out to Trek and MRP, it became clear that the guide had been improperly installed from factory, with 5mm instead of the intended 7mm of spacers between the frame and the guide. 2mm didn't seem like it would make much difference to me, but after changing the spacing and taking the bike to Pemberton for a huge weekend of riding, I was unable to get the chain to drop again. The trails up there are rough, fast, and full of good chain-challenging moments, so it's possible things are fixed for good.
A rider as capable as you reviewing this stuff is gold 👍
Thanks
Did Trek test this bike?
@@chadclark2070 Probably not
Well that means that marketing is a thing and real life is another. I have been concerned about all those high pivot trending, at least for Enduro bikes. This shows that they have their use, but not for every use. Thanks for a clear review 🤘🏻
@@fabriciofracchia6732 I own a Cannondale Jekyll and have never had an issue with the chain, stays on great. The only issue I have had is a linkage bolt popping out, but that was my fault as I probably should check them more lol!
This is great content Lewis. Honest reviews are appreciated and I hope you will have a resolution soon. In the meantime, you can reminisce about Balfa BB7 frame design and how well it worked. That and the ancillotti were the best frames I’ve ever had. They don’t make ‘em like they used to :)
Thanks
The problem with an issue like that for the average Joe is they are at the mercy of the shop they bought it from and in my experience they can often give you a million reasons for not properly sorting the bike, you could be left with an expensive lemon.
Hopefully trek will sort it out, seems to be they could greatly improve it by making the idlers better. Hp bikes drop chains a lot anyways and not too many people seem to complain so I think most people will be ok.
Facts, I recently bought a high pivot bike (I won't name the brand or bike yet until their customer service gets back with me) and the finish is atrocious. On the surface, it's a beautiful bike, but the brake hose routing through the rear triangle has a sharp bend in the tubing (it has an internal tube to guide the hose through the seatstay). It also is rough and may abrade the brake hose. The head tube was faced so thoroughly that the headset compression ring dust cap doesn't cover the facing (so you see raw scraped carbon around the top of the headset). They also did not pack the bike with everything (wrong tire, I received a 27.5 tire for a 29er bike and no PowerLink for the SRAM t-type chain). Now, as a shop employee, I know that we'd build that bike up, get a tire that fits and order a t-type power link, and do what it takes to route the brake hose. We'd sell the bike as is. The customer would always have trouble with the rear brakes, I have no doubt in my mind. As it stands, I have no clue what I would do if the manufacturer doesn't warranty this faulty frame. I guess I would sell it and let the buyer know what they're getting, and name and shame the bike man. Still, the shop is the ultimate arbiter and they aren't always looking out for the end user's best interest. I doubt many shops would send the bike back, in my case.
If I was Lewis I would send the video to Trek and make them pay for that Lemon .. 🤬
@@DarkFeedFPV Lewis has enough viewership that I'm certain this will get back to Trek and they'll make it right. 😁 But! Never buy Trek.
@@seanrequiredfieldcannotbel1362 so true, I will never be a trek again
Coming from a bike mechanic of over 15 years, the only thing I can see from your slow-mo video is slack chain between the top idler and the chainring. This could only be caused by a sticky freehub putting forward rotation on the chain, otherwise the freehub should always spin back taking up any slack on the top side of the chain. This could also be caused by the chain jumping on the cassette and causing it to "jam", pulling on the derailleur and then putting slack chain on the top.
I would try a different rear wheel before blaming the bike, but it could also just be the bike ;)
Sounds smart and what is actually about changing all the parts of the drivetrain ? You could take the same line of parts but just new ones...could also just be that one tooth, one chainring what ever is maybe weird produced
Hi, I dropped into the comments to say something similar. Watching it at 0.25 speed you can see on the 1st chain drop the slack appear between the cassette and the idler that then whips round the chain and throws it off.
Based on that I would say that it's a freehub or the bearing in the idler that's to blame.
This has got to be it
@@jimthesa1ntyou both close but the issue is actually from the rebound of the bike, when he compresses off the lip his chain length increases, then as he unweights the bike with a fast rebound the chain is left to become loose in free space as the cassette and front sprocket distance decreases rapidly, leaving the whole chain to become weightless and floating off.
Only solution here is a idler pully with a fast acting tensioner to remove the slack during the rapid change from rapid decrease is chain growth! The tensioner would have to be very responsive tho!
The tension provided by a derailleur is deffos not fact acting enough through such a large distance needed to pull that chain back tight.
Thank you so much for providing a real review of the bike; it’s so hard to find unsponsored reviews
I fully agree with you on this man,I was considering buying one so thank you for the info man! Too expensive to be that bad...
What I’m here for! Just sharing my personal experience
Jeepy have a look at the hope hb916 if you're in the UK. Similar looks but it's supposed to be better.
So I have been riding the Forbidden Dreadnought for 2 years and switched back from the old gx AXS to a shimano drivetrain. My collegues on bikes with "normal" suspension designs never had issues with AXS. For me it seems that the clutch on at least the old AXS is just too weak and cannot be adjusted at all. I did have a couple of chain drops (I am not using an idler behind the chainring) on rougher stuff but never again with the adjustable clutch on the shimano derailleur. The bike was loud as hell as well because of the AXS derailleur moving around so much and the chain slapping. I am not sure if the transmission is the same though. On your slow-motion footage it almost looks like it. If you play back the drop footage really really slow with youtubes 0.25x speed you can clearly see that the derailleur stays up top for after the initial impact and thats seems to cause the loose chain to come of after the following chunk. Before that right after dropping off the slab when the rear is rebounding and getting shorter (as on pretty much all HPP bikes) the loose part of the chain seems to wander forward beyond the idler on top. Before the impact on the floor the chain is already pretty loose between the idler and the chain ring. If you ask me, I'd try out a drivetrain with a stronger adjustable clutch for chain tension.
btw you can go through videos on youtube frame by frame with , and .
After looking at the footage im 100% sure that, like you said that the chain cant go back fast enough when rotating the crank backwards wether its due to to the top pulley positon or too much friction in the drivetrain. You can clearly see the chain links making a little "v" on the chainring already in the air, and then the impact on the ground + the loose chain around the chainring makes the chain come off.
Clutch on the derailleur is likely not stiff enough. My axs had zero chain offs until a few weeks ago, now it happens occasionally. Checked the rear mech and it there was little resistance compared to a friend's brand new (also replacement due to bad clutch) derailleur
This
I added T type and MRP to my dreadnought a few months back. It’s mullet with ziggy so almost identical in appearance to the trek. I have smashed it at dyfi week in and week out and had no issues at all with the drivetrain. What you have experienced absolutely should not be happening. Hopefully trek can sort this for you as there is clearly some design issue that’s been overlooked somewhere. Great content, fingers crossed for you as 5k is a lot of time and effort to go down the drain.
Dreadnought FTW!!
Could it be bad/sticky bearings on the freehub body? That would basically cause the chain to have more tension at the bottom and possibly slacken at the top. Add the high-pivot+idler design which shortens the axle-idler distance as the suspension compresses, further exacerbating the low tension and slack at the top, that's basically your recipe for a dropped chain.
IIRC from some of the tech talks I've seen on this bike, Trek has designed the rear suspension with the lower idler to intentionally limit an increase of chain tension throughout the travel (similar to how the upper idler eliminates pedal kickback, the lower idler prevents lower chain tension from imparting forces on the suspension system via the derailleur cage). They showed clips of them cycling the suspension through the travel and the derailleur cage did not move.
I'm sure a big brand like Trek has tested the hell out of the bike, but maybe an increase of chain tension as the suspension compresses would keep the chain on better?
Its common knowledge chains come off from side to side movement, basically the wide link of a chain will hook on the top of a chainring tooth and derail itself.
The top pulley on the Trek doesnt have narrow wide teeth to stop this, the teeth are also very shallow, the lower idler is even worse.
Having mega tight clutch tension would help, if it was adjustable, but basically the design is just flawed.
Running two chainrings with narrow wide teeth can cause issues if the chain skips, but it should never skip like that - the top pulley needs to have a fully wrapped around guide if using standard teeth.
The bottom guide needs to be ditched or again use a much taller guide to stop the chain jumping off - one look at the Commencal V5 will show you whats necessary to overcome the issue.
Hey Lewis, I don't know if you'll see this but pinkbike had problems with it in their huck to flat field test. They realigned the lower pulley wheel by 2mm and apparently solved all the problems.
My buddy just got the new slash and had been riding the hell out of it. He’s like 275 pounds and this bike has been an absolute tank for him. No drivetrain issues yet
Is the top idler pulley narrow/wide? I have a Norco Shore 2 and had similar issues with the chain always coming off. I concluded it was because the idler pulley wasn’t narrow/wide. Bought the Forbidden idler and haven’t had my chain come off since.
Check the Nm of the derailleur Lewis
Supposed to be 35nm, that new sram doesn’t work properly otherwise
I've called Trek out on a couple of frame design issues in the past, they sent out replacement bikes both times.... Same issue, both customers got refunds and bought a different brand of bike 💁🏻♂️
What was the issue? What were the bikes?
As a bikeshop mechanic for more than 10 years - when you buy a bike from a shop the mechanics at that shop will have removed the bike from the box and fully checked the bike is built correctly and the gears and brakes are functioning as they should. After a break-in period the shop will usually offer a “free first service” to dial in anything that might be wrong (like indexing adjustment).
If the bike has come from Trek’s overseas manufacturing facility straight to you in a box then anything might be wrong with it. Typically these are thrown together as quickly as possible with little to no grease and shipped to distribution centers to be correctly assembled by the bike shop that is selling it.
This does not seem to be incorrectly assembled - this seems like a completely flawed design that will never work…
There are 2 types of boxed new bikes, manufacturer to dealer, that works as you've described, and manufacturer direct to consumer, like YT, Canyon, Trek, etc. Lewis is right in that the bike should be ready to ride out of the box, BUT I think that it's still a good idea to have direct to consumer bikes checked out by a mechanic. Nevertheless his issue seems like it may be a design flaw. High pivot mania is adding so much complexity to mountain bikes for so little advantage. World cup downhill and enduro races are still being won just fine on traditional linkages where any real advantage would show itself in such slim margins.
I worked for a Trek dealer in the UK - I was unaware they had moved to a DTC model - where I live now, in the USA they have done the opposite (they are buying the local shops and rebranding them as Trek shops).
When I left the UK the only real DTC brand was Canyon - and every one of those we unboxed we would charge £150 to put together and they were terrible…
there is a Trek dealer about 30 mins drive from Peebles, used to be an independent shop, as you say@@workshopninjathe1st
I struggle to imagine that a flaw this large would make it through Trek RnD (totally possible but seems unlikely). The only thing I can think of is that you are unlucky and have copped a dud frame with sections of the tubing out of tolerance. I would personally pull the frame apart, and when rebuilding it, check that all bolts line up correctly and go in easily. If there is any fighting required you know they didn't have it in the jig right when welding or something. Definitely a major PITA
I got to demo the Slash 9.8 AXS the day it was launched. Rode some of the roughest stuff in the Lake District and had no issues with the drive train. I even tried to shift gears as badly as I could - under load and in quick succession - the T-Type was flawless. Bike road great. That being said...my take-away was I wouldn't buy one 'cause I'm rubbish at mechanics and there's just so much going on with the drive train I'd be stressed out about cleaning and servicing it.
Trek store mechanic here, the only thing that I can think of is the eye to eye size of the new shock you installed. Is it identical to the stock shock? If not this could affect the rear axle path during compression. Also I would recommend checking the freehub body, if it doesn't spin freely it can cause the chain to bunch up between idlers when you stop pedaling suddenly. Best of luck.
Great review! Thank you for diving further into this issue. Good troubleshooting process! Curious if Trek comes out with more information soon.
That’s super weird! I have the exact same bike and size. (I sized down to ml for a more playful bike as well) I’ve done trails way more chunky than these trails shown and I’ve never had my chain fall off…
If you pause it on the drop the chain is already off before you land. Something is making the chain slack around the chainring. Other people have the said the mech, could also be the chain is a bit damaged or has a sticky link, and maybe the top guide is catching on the chain.
I went frame by frame at 5:25 and the chain between the chainring and the top idler wasn't tight for the whole video clip. I suspect that the derailer can't put enough tension on the chain to overcome the drag in the free hub. Have you checked how much tension your derailer has vs other derailers? Maybe you got one with a weak spring or maybe that model just has a weaker spring than others.
Sounds like the GX AXS isn't a good fit for this bike and the XT Shimano might fix it. Would love to see someone test this out.
Since these derailleurs don’t have B tension getting the rotation of the derailleurs correct and torqued correctly is imperative. Being slightly off or not tight enough so it rotates messes the whole system up. A high pivot bike with all that CS growth could be pulling the derailleur forward over repeated hits and putting it out of adjustment.
I would have thought the idler should be sprung loaded to take up the slack when the bike is heavily compressed?
I think it very well could be the clutch in the derailleur. I don’t think it’s allowing the correct amount of tension which is allowing play in the chain and allowing it to come off under bumps. I think a potential quick and easy thing to do would be installing a different transmission derailleur from a friend or a bike shop demo bike and give that a try.
Good call.
Great to see honest reviews, there are so many industry plants with so many biases pushing new parts and bikes onto consumers, mountain biking is fucking terrible for it at the moment. These reviews are a breath of fresh air mate. Cheers!
slowmo on the drop if you go through it frame by frame you can see what the issue is. There is excess chain between the chainring and the idler when in the air. As soon as the rear wheel hits the ground that goes slack and comes off.
At 5:28, look at the bit of chain between the high idler and the chainring. It's NOT a straight line. As if the cassette rotated slightly in the drive direction forward when the suspension unloaded, pushing the chain towards the high idler (but your chainring was stationary when going off the jump), and that introduced slack inbetween the high idler and the chainring. It's very obvious. When you landed, that slack was still present, and the chain merely stepped off the idler from the impact alone. Trek almost needs to add yet another tensioner between the high idler and the chainring to prevent a backpedal induced chain jump-off
Noticed the same thing, and I think there's an issue with a tight upper pulley or maybe free-hub, chain getting stuck somewhere in the derailleur, or simply weak chain tension. Lewis should to backpedal sharply and try to find what could cause this. Nothing what a competent bike mechanic couldn't solve.
Damn, good eye. It's like the hub isn't freewheeling properly and is pushing the chain forward but it has nowhere to go because the cranks aren't moving.
a draggy hub cassette driver perhaps.....@@bearded4glory809
The chain was coming off the front of the chainring before he even hit the ground.
@@krushiXX Yup, you nailed it. The free-hub has more drag than the idler. The chain is being pushed forward by the cassette, rotating the idler, which gathers the chain up at the stationary chainring, creating enough slack to pop the chain off. I'd try a different rear wheel.
My bike used to lose the chain in the same way as well. Turned out it was a worn chainring and the tension in the derailleur was very weak. I now run shimano and NEVER have a problem becasue there’s an actual clutch
Those slow mo’s at the start just make me want to get out on my bike! It’s great to see you back doing DH again and also some gnarly free ride.
And what should the firm Trek do now? The bike is on sale! Not very good support Track ! I generally dealt with a crack in the frame Slash 5 but was not the first buyer, when they found out it, they stopped responding !
Man I’d look into a Santa Cruz nomad. They have an ever so slightly rearward axle path. Just went to one from a RM Slayer. With it now being mullet it would tick all your boxes and not have any ridiculous drivetrain nonsense going on.
The SRAM tech paper for frame builders says UDH (Universal Derailleur Hanger) is not for high pivot idlers. It says the chain needs to be horizontal. Trek neglected to read this apparently.
idk... i'd try 32 tooth chainring for a little more contact w the chain and double check narrow/wide teeth line-up correctly with the chain? I ride the Forbidden Dreadnought high pivot with Cascade's chain guard/retention and Forbidden's Race guide, and have had no problems like this whatsoever. hope this gets figured out for you
Hi, My name is Devin Armstrong I am 15 years of age and live and ride in Whangārei, New Zealand. I really think you should try out a gearbox bike if you’re still looking around. I would recommend one from either zerode a company out of New Zealand designing and testing the bikes in Rotorua. Cavalarie a French company using the less common effigear gearbox or viral bikes with their new optimist 160. The chain or belt depending on which company you go with should be impossible to ever drop as the bikes are all technically single speed on the outside. Effigears gearboxes are unable to shift under load however the pinion gearboxes found on the other two bikes can. The optimist 160 is not yet released but is specked with pinions new smartshift gearbox Sean on the gamux dh prototype. Zerode has not yet publicly announced the use of these gearboxes however I have had a chat with them and they expect to be using them in January next year. The suspension performance on all these bikes is next level thanks to the weight of 12 gears, a derailleur and heavy chain being deleted from the back wheel making small bump sensitivity insane as shown in a drop test on zerode’s UA-cam channel. Personally I would recommend a zerode as they have been around for many years and the optimist is viral’s first full sus bike. I think everyone’s riding can be drastically improved on a gearbox driven bike and have recently started a job to save up for a zerode katipō and think gearboxes are the future of cycling especially with pinion’s new technology.
i was thinking of replacing my 2017 giant anthem, but i guess i hold on to it a little bit longer.
it has never dropped a chain in the 7 years that i owned it.
Trek has gone downhill the last few years in my opinion.. many friends have had broken frames..wheels etc. That’s a nightmare having problems with a brand new bike!!!
Could you put the bike on a stand, unbolt the shock at one end and then see how the chain moves as you lift the rear wheel up and down through the travel with the chainring held static. That would replicate what happened on that big landing. Would be interesting to see if big amounts of slack are introduced between top idler and chainring.
Lewis uploaded another video introducing the bike a couple weeks ago and included a demo video from Trek that showcase the chain movement / pivot like you've described, was pretty interesting
@@AJR-gg just watched the Trek vid. It doesn’t address what happens to the chain between the top idler and the chainring. I think there would be value in disconnecting the shock to do an experiment. Also what happens if the pedal rotates slightly fwd or back during the jump - does mech. Front wheel spinning fwds too so that cassette can’t rotate back. 🥼🥽👨🏻🔬
have you tried a new derailleur?
The slash's idler is on the arm and not the pivot meaning the location of the idler moves, basically acting like a weak clutch between the chainring and idler.
I believe they had similar issues on the session and why we seen prototype arms on that bike a few times.
Believe it or not I think the mech clutch is not allowing the chain to maintain tension
When people have the chain coming off and down the cassette while backpedaling its usually the brand of the chain. Do all spec versions run the same chain?
Are both idler pulleys narrow wide? It definitely sounds like the chain is rolling off the pulleys because chain growth is eliminated that means chain tension is much much less under compression. Believe it or not I think the mech clutch is not allowing the chain to maintain tension
Bikes may come assembled but that does not mean we shouldnt go over the whole bike in detail and re torque everything to the proper specifications. I like to think of a box build as a "shape forming" and it is up to the shop and the rider to double down and check it again.
one other thing from the Slash service videos..... they say the "lower shock mount and shock need to be torqued to spec with the Bike OUT of the stand and on the floor, this allows the shock and mount to centre itself under the weight of the bike". Not sure if this would make any difference to the issues you've been having but thought I'd mention it anyway.
Before you bin in. TRY THESE: Change the chain to an XX1 T-Type. Upgrade to an aftermarket Chainring. To me, its like the chain itself is too wide/not engaging in the chainring teeth. You don't see this sort of thing on Eagle or Hyperglide II chains.
Several rides around Inners with wolftooth, and the chain hasn't dropped once. Best 80 quid I ever spent on the bike.
I'd suggest trying it without a axs transmission setup to see if the problem still happens.
If you can find an older SRAM derailleur try it with that. I've noticed the clutch in newer SRAM derailleurs aren't as taught as they used to be so the chain is just too sloppy.
I think pivot has don't high pivot right on the test bikes using 2 chains like it's alot more complex but remove pretty much also issues of having such a big chain
Try a mechanical shifting deralieur with a udh hanger. That way you have a way to properly setup b-tension which t-type really doesn't have.
Weird to me that the bottom pully can’t be moved closer to the chain ring like back with old E13 chain guides. For the top, the guide should cover more of the pully wheel for when we pedal backwards granted chain line should fix that. But I won’t touch one of these at my shop for another few years.
I ride the Session HP since a while now and had issues with the derailleur clutch not providing enough tension. Changed the deraileur and problem was solved.
Maybe try a different rear mech as others also mentioned.
Hope trek reach out and explain this…I have a trek fuel ex 8 from 2017. Things a dream. But far simpler than the slash. Ain’t broken….don’t fix it. It’s like they enjoy reinventing the wheel.
As the suspension compresses the chain is becoming too loose, this is probably because the rear mech can’t put enough tension around a chainring and two idlers, when the rear mech is in a more vertical position the chain will be pulled in a steeper angle compared to the bottom idler, this it’s when it will probably be jumping off the top, and when the rear mech is more horizontal, like when on the 10 or 11 tooth there will be more slack in the bottom and that’s why it’s jumping off the lower idler. The riders trek used in testing maybe don’t race enduro , trek should have made sure that the components were compatible with there design. Bike design looks to complicated, and heavy. Keep it simple and easy is best
I think the problem is the flattop chain from the transmission because my homie have also a slash with a shimano drivetrain and his chain never felt off
40 pounds ! What a tank I'm still riding a 2020 slash 9.9 sram eagke gold, lyrik ultimate, roch shox super deluxe shock, xt 4 piston.brakes, renthal cockpit , dt swiss 240 hubs 511 rims, minion dhf exc+ with cushcores. Bike weighs 30.5 pounds. Pedals very efficiently and rails downhill Chunk etc. Every new bike I test rides very inefficient feels like the brakes are dragging .
Bought a Trek Stache a few years ago. After three replacement frames it was determined that the chain rubbing against the stay was a design error. Didn’t work with SRAM 1x. You have to wonder about Trek’s R&D. I’d never buy anything else from this brand.
A few things that fucked with my dreadnought: broken hub axel. Derailleur loose.
Also, is it possible your rear triangle was hit in shipping? Alloy bend.
The box it came in didn't show a scratch or dent at all.
I just rode my Druid v2 this weekend. Descended over 10k feet and not even a single worry of the chain coming off.
Interesting noticed a new people having issues with the T-Type chain dropping.
I'd try Shinano groupset or the older SRAM see if it still has issues.
If you use the app to calculate the chain length it does say it’s compatible with chain rings 2 sizes bigger. Maybe test the app with a 28 tooth and see what it spits out for chain length I’m guessing it could be shortened or toss on a bigger chain ring for a test lap.
Either way super annoying and shouldn’t be an issue on a 6-13k bike at all.
Finally an honest rider! 👏 ❤
Idlers cause unwanted tension in the chain and they break constantly. Single speed for the win. Canyon Torque does the same thing with no idlers at all.
I bought a new, very expensive bike this last January from a very reputable brand and the derailleur bolt kept coming loose, no matter how well setup it was. I even replaced the bolt with the top of the line version and the problem persisted. Ended up replacing the whole transmission for a different brand and it has been working flawlessly for months. Rumor has it that the OEM components were not completely compatible with this specific frame, but they specced it on it anyway... This made me mad, such a lack of care on bikes that cost more than a small new car...
Pop a cheeper drivetrain on it and see if the problem persists. That way you can possibly identify a frame design issue or a weak drivetrain issue.
Same thing on a Dreadnought with prev gen GX AXS here, only thing that stopped it was the updated 'Race Guide' for the idler.
Okay... I've decided to 'jump in' to this situation... I have a few thoughts(forgive my ignorance as the case may be): 1. Weather it's side to side, or top to bottom - there is too much play behind\above that top chain guide & pulley... & the proof regarding that(even though I haven't seen the bike\drivetrain in person), comes from the FACT that in order for the chain to come off, said chain MUST rise UP off of the guide pulley(so weather you glue rubber or plastic on or adjust the guide - reduce the space above the guide pulley)which 2. It doesn't seem as if said guide pulley is of a narrow\wide nature which should further reduce drops(as I'm certain you know by now)... Anyways 3. I had the same thought that you mentioned regarding reducing chain length - but since you said it's in order, how about something being wrong with the clutch or general tension of the derailleur? 🤔
Check hub to make sure it’s not binding in any way. Check derailleur make sure the clutch actually has resistance. You’d think sram would make sure that every T type drivetrain is 100% perfect but now days I doubt that. I see just as much warranty issues from high end components as I do low end components. You’d think trek would have that dialed in or at least have a inside tech that could help diagnose it. I get the frustrations tho.
I think the gx trasmition isnt desinged for 2 idlers, because its a lot harder to pull the chain with to more idlers. You could try it without the lower idler like most other high pivot bikes do.
You need both idlers because otherwise there is almost no chain wrap on the front chainring. Its the same reason why the original druid had a guide at the bottom. On the druid v2 forbidden moved the top idler back so that there was naturally more wrap so they could ditch the lower guide.
Kinda crazy that Trek didn't have this problem in all their testing.
also I had a similar problem with an older bike, I think a much shorter chain, and much less lower guide tension would do the job, on the lower side, the chain should be almost horizontal, just a bit of pullup on the chain, and maybe move the lower guide closer to the chainring if possible, that decreases the tension on the derailleur, if the springs in it are less stretched, the derailleur can much better actuate. you can confirm the latter with switching over to a saint derailleur for example, because they have bull strength springs, that can somewhat work with very bad chain tension. if it doesn't occur with a saint, it's probably about chain tension, and apply stuff I mentioned above(hopefully)
@@bearded4glory809 bingo. And I just built a Druid v2 and smashed it all weekend and not a single issue w the chain
Move the lower idler in between the high pivot and chainring and add a tensioner
I've designed a high pivot bike, you need to have the lower idler as high as possible to have the lower chainline as lose to passing thru the pivot. This reduces the amount of "stretch" thru the travel. Then set chain as short as possible.
think this could be from the idler moving away from the chainring in compression? if its not happening all the time, could be a function of that and shock speed...?
Hi 👋
I recommend to try a shimano divetrain with a shimano derailleur bcs the clutch is way tighter
Why do GX rear mechs always look bent? I upgraded to X01 and couldn’t be happier.
Have you gone to the trek store near you to get the shim to fix the issue. They have a shim that moves the idler out more to stop chain drop
I agree with what someone said here about the clutch being weak having seen in that slow mo just how slack the chain is getting but unlikely that, maybe just nature of those new derailleurs. However, totally agree that the upr idler guide should be further forward OR if you look at Yeti’s proto DH bike have a guide similar to that over the upr idler. They may have had a similar issue and made that to fix it
You have to think too, the longer the chain the harder the clutch has to work. Shimano clutches are adjustable for this and SRAM ones aren't.
@@kingflynxi9420 are they adjustable for the chain length? I thought only for how hard it was for it to ‘break away’. Chain length shouldn’t matter as, if the chain is the correct length, won’t affect the angle/position of the derailleur in each gear and will always be the same regardless of length.
Completely right in your analysis. If it is a bicycle to take it to its maximum and that an anchoring system does not work, nor buy it Greetings and it was an expensive investment
I`m on a high pivot bike myself (deviate claymore) and the chain didnt come of once. The bike is overall realy good and i only can recomend it, if you want to try out another highpivot bike.
Have you checked if the cage on the derailleur is straight? A mate also has the new gx transmission and his shifting was garbage and the chain came of all the time after he hit the cage slightly. We replaced the cage and its working good now.
Checked out all good at the bike shop yup
The problem is Trek’s high pivot design. Due to the location of their idler, being too forward, it is causing your to chain drop. A larger chain ring could solve your problem
If the free hub body is not working properly that could happen, maybe you could check it out and make sure that as soon as you stop pedaling the cassette stops right away if it doesn’t then it would push the chain forward and will make it go off. I watch minute 5:28 at x .25 an zoomed it, before you land i noticed that the chain looks weird, is seems like there is no tensión from the high pivot to the chainring that why I suspect of that. Industry nine is easy to open, it only has a plastic seal and you just pull it and get it out.well is that same seal the one that if it doesn’t saddles well gives problems
Mega review, thought the flow between talking to camera and related bike shots was excellent
I wonder if its a frame flex issue? Trek have probably tested this setup to death with a carbon frame but I wonder if an aluminium frame is just produced without any real testing to offer a cheaper alternative? we all know carbon frames are stiffer, so maybe it is frame flex that's causing it.
It’s like the age old saying, If ain’t broke don’t fix it 🤷🏼♂️ companies always trying to reinvent the wheel and it always just causes more headaches and potential failures and problems.
I planned to order one of these later today. I'll hold off for now and consider other options.
Did you end up doing a full review of the Spindrift?
Well if you want a testimony for the spindrift, everyone I've watched on youtube loves theirs, and the guy I ride with has one. It feels very capable and hasnt had a single issue
my mate has a gen 6 slash but the base model with shimano. he hasnt had issues with the drivetrain but it seems all ttype models have issues for the fact that ttype doesnt really have a b-tension
get a metal saw and remove the horizontal idler pully next to the crank(the one that says MRP)
NGL, it does look useless and like you said is stretching too much the chain/derraileur
That’s heartbreaking, those idler gears seem like really new technology that perhaps havnt been fully vetted
Its surprisingly common in the industry for bikes to need assembly and tweaking out the box by a qualified mechanic. Even the legal classification of a 'true' wheel for sale is quite wide and ive had to adjust spokes out of the box, bleed brakes, add spacers and trim chains. That being said these problems on your bike are inexcusable and quite baffling, im leaning towards a design flaw somewhere since you checked so many different parameters.
The top Idler Ideally needs to be narrow wide that will stop it dropping off the top. As for the bottom one it looks like it could do with being closer to the chainring, is it possible to adjust this? I have a GT force that is very similar (hight pivot with idler) and have no problems with the chain coming off. On the GT the top idler wheel is narrow wide and I have set the chain guide up so it is very close to the chainring.
Since the drivetrain uses both sides of the chain, I wonder the new Sram chain may be an issue because it is smooth on top and shaped differently. Trying an old style Sram chain or Shimano drivetrain might make a difference, I don't know. That Sram chain is just released new tech, maybe during testing, Trek only used older style chains. Just a thought 🤔
What happens if you put a “normal” cable actuated drive train on?
If you pause the video at 5:28...you can see the chain is off before the bike had landed so chain started to come off on way into the feature.
Angle isn't lined uo earlier to see what has happened
i have a gt force with gx eagle and luckily ive never had an issue with my high pivot
the recent article on Pink bikes gives you an indirect nod..... here' the fix.... incase you didnt read it already.
MRP MXg Chain Guide: This innocuous seeming lower roller may have proven to be the most controversial element of the new Trek, given the issues quite a few early users had with the chain dropping off the roller during fairly normal riding scenarios. I had this happen quite a few times during testing, both in the bike park and on lower speed tech trails in the area - all to some frustration.
After reaching out to Trek and MRP, it became clear that the guide had been improperly installed from factory, with 5mm instead of the intended 7mm of spacers between the frame and the guide. 2mm didn't seem like it would make much difference to me, but after changing the spacing and taking the bike to Pemberton for a huge weekend of riding, I was unable to get the chain to drop again. The trails up there are rough, fast, and full of good chain-challenging moments, so it's possible things are fixed for good.
@LewisBuchanan thank you for your reviews. chain issue aside, how does it compare to norco range on a trail?
Your chain was off before you even landed the drop. Something is faulty or damaged. Bummer, me and two buddies have this bike, we love it and have had no issues other than with some of the SRAM stuff.
Get back on the Optic! I went and bought one after watching your videos so cheers for that mate
Interesting that @5:26 you can actually see the chain bunch up between the idler and chainring as the suspension comes to full extension, quite a visible kink in the chain. As you come past the camera you can see where one of the links is already popping off the narrow wide chainring and that's the one that gets thrown as you land and compress the suspension.
I saw people commenting about the new derailleur is not build for this kind of bike, what if throw in a cable actuated derailleur and see if it will fix the issue. May it be sram or shimano