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  1. #1
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    Fuel EX 29er Drivetrain - Chain Roll Off

    Just a heads up to everyone riding the new Fuel 29ers. I've had the EX8 for a while now, and recently when in the small ring up front the chain would come off the pulley on the rear derailleur arm and wedge in between the pulley and the arm. Took it into the LBS and the first guy that looked at it thought it was bent so he adjusted things a little. Rode it again and it was even worse.

    Brought the bike in today and a different person was in the shop and knew exactly what I was talking about. Apparently Trek is putting the wrong chain on these bikes. The Shimano drivetrain requires a Shimano chain, but they are putting a KMC chain onto them. Apparently my LBS talked to someone at Trek about this awhile ago and they said "yeah, we know these don't work well together so if you have someone coming in with problems let us know and we'll replace things".

    I'll either be getting a new rear derailleur or new chain, not sure which yet but the shop is at least taking care of it...just a heads up if you have one of these bikes and are seeing the same problems.

  2. #2
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    Interesting, I had gear changing issues on the rear since I bought my EX8. Sometimes the rear would start making 'chunk' sounds when shifting to a larger gear and not shift for 1-5 seconds. Guiding it by holding in the shifter usually worked a lot better but tended to cause double shifts a lot more when in a rush.

    Talked to the LBS quite a few times and they tried adjusting it and it did work 'mostly', finally decided to make a video of it where I had it happen while the bike was in the air. Showed it to the LBS and he then took a closer look at the chain and almost ripped it off and put on a Shimano chain. Bike started feeling way more responsive after that, probably due to the chain being better aligned with the cogs and the shifting issues are gone.

    He also said he'd put it on the warranty since the chain was causing such huge issues.

  3. #3
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    for what we pay for these bikes youd think they would come with the proper chain.
    live to ride ride to live

  4. #4
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    Yeah, that is a little frustrating. I've already had two replacement wheels on the bike and now this. Kinda thinking I might as well buy the next bike from BikesDirect

  5. #5
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    What issues did you have with the wheels if you don't mind?

  6. #6
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    All on the rear wheel. The first one kept breaking spokes and then having spokes loosen up a LOT. It was swapped out for a new one. After about 100 miles I broke a spoke on the new one, and this time a lot of the spoke holes in the rim were cracked. They sent an upgrade this time, the Bontrager Mustang. Got 40 or so miles on it now with no issues.

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    what was the problems with the wheels ?
    live to ride ride to live

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    The cause of the problems, that I don't know.

    The first wheel kept having spokes come unscrewed. It was re-trued/tensioned several times and the shop even rebuilt it entirely once to reset tension.

    The second one had cracks on the spoke holes after a small number of miles.

  9. #9
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    Tjih I've put about 400 km on mine and so far the only issue has been a out of center alignment issue that the LBS corrected. Wouldn't be surprised if it was caused due to a rather heavy hit to the spokes that a branch caused, I'll have to keep an eye on the rear wheel though.

  10. #10
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    Excuse my language, but damn it! My chain has been dropping constantly and I kept assuming it was just me knocking it out of adjustment. Lbs has done adjustments repeatedly, and I've even switched my ex8 29 to an xt crankset (2x10). The fork is back at fox for another repair so I can't ride it at the moment anyway but I'm going to have them talk to trek at the lbs.
    I'm glad you posted this up, I'll talk to them about it today thanks!

    My rear abp axle kept coming loose, and now the rear hub feels a bit wobbly somehow. Like it has some lateral play even if the axle is cranked down very tightly or even if it's loose. Strange stuff.
    I love the bike, but it sure is fighting me!
    10 Gary Fisher Cobia - 13 Trek Madone 5.2 - 14 Trek Fuel Ex8

  11. #11
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    Quote Originally Posted by multitool View Post
    for what we pay for these bikes youd think they would come with the proper chain.
    +1, Has Trek ever had a representative on these forums?

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    Quote Originally Posted by 722ish View Post
    The fork is back at fox for another repair so I can't ride it at the moment anyway but I'm going to have them talk to trek at the lbs.
    I'm glad you posted this up, I'll talk to them about it today thanks!

    My rear abp axle kept coming loose, and now the rear hub feels a bit wobbly somehow. Like it has some lateral play even if the axle is cranked down very tightly or even if it's loose. Strange stuff.
    I love the bike, but it sure is fighting me!
    Just as a side note the CTD on my fork broke on the second day, apparently a manufacturing error so it was corrected on warranty in a week.

    I'm pretty sure I've seen some posts about the ABP thing for another bike which sounds similar to your issue so you might want to search around.

  13. #13
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    I have the stock KMC chain on my 29 EX9 XT drivetrain, and it runs very well. In fact, I have not had one dropped chain and the shifts are as good as I have ever had (significantly better than the X9 on my last bike)....I just thought it was Shimano marketing to require a Shimano chain, but maybe it would run even better with one. Anybody switch it out for Shimano?

  14. #14
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    Quote Originally Posted by Haymarket View Post
    I have the stock KMC chain on my 29 EX9 XT drivetrain, and it runs very well. In fact, I have not had one dropped chain and the shifts are as good as I have ever had (significantly better than the X9 on my last bike)....I just thought it was Shimano marketing to require a Shimano chain, but maybe it would run even better with one. Anybody switch it out for Shimano?
    From above I wrote:
    Interesting, I had gear changing issues on the rear since I bought my EX8. Sometimes the rear would start making 'chunk' sounds when shifting to a larger gear and not shift for 1-5 seconds. Guiding it by holding in the shifter usually worked a lot better but tended to cause double shifts a lot more when in a rush.

  15. #15
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    Quote Originally Posted by NetQvist View Post
    From above I wrote:
    Interesting, I had gear changing issues on the rear since I bought my EX8. Sometimes the rear would start making 'chunk' sounds when shifting to a larger gear and not shift for 1-5 seconds. Guiding it by holding in the shifter usually worked a lot better but tended to cause double shifts a lot more when in a rush.
    I might stick with the EX7 if I purchase a fuel, perhaps these superior components I have been told are on the EX8 are not so superior.
    Last edited by bob_m; 09-27-2013 at 08:10 AM.

  16. #16
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    Quote Originally Posted by Haymarket View Post
    I have the stock KMC chain on my 29 EX9 XT drivetrain, and it runs very well. In fact, I have not had one dropped chain and the shifts are as good as I have ever had (significantly better than the X9 on my last bike)....I just thought it was Shimano marketing to require a Shimano chain, but maybe it would run even better with one. Anybody switch it out for Shimano?
    I was very happy with the shifting for the first month or so with the bike. I didn't have any issues and I was impressed with how solid it was. But it started to get really bad over a few weeks...

  17. #17
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    Re: Fuel EX 29er Drivetrain - Chain Roll Off

    Quote Originally Posted by Omicron View Post
    Apparently Trek is putting the wrong chain on these bikes. The Shimano drivetrain requires a Shimano chain, but they are putting a KMC chain onto them. Apparently my LBS talked to someone at Trek about this awhile ago and they said "yeah, we know these don't work well together so if you have someone coming in with problems let us know and we'll replace things.
    Ahh. I am on a 2013 26er EX8, and it has the noisiest chainline. It was inspected/adjusted, no real change. Sounds like it is rubbing, but it is plenty clear. I suspected wear-in, or dirty or ??, and noted the KMC chain, and figured I'd swap it. Now, I'll ask Trek to swap it for me.

    Sent from my DROID RAZR using Tapatalk 2

  18. #18
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    In the month I have had my EX 9/29 I have put on a little over 250 miles with no shifting (or other mechanical issues) at all. I do get an occasional "klunk" sound when shifting under load but no dropped chains at all.

    On another note my older EX 8 (2009) does have a really noisy chain line.

  19. #19
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    Quote Originally Posted by Haymarket View Post
    I have the stock KMC chain on my 29 EX9 XT drivetrain, and it runs very well. In fact, I have not had one dropped chain and the shifts are as good as I have ever had (significantly better than the X9 on my last bike)....I just thought it was Shimano marketing to require a Shimano chain, but maybe it would run even better with one. Anybody switch it out for Shimano?
    Same here no issues with my KMC chain and shimano derailers.
    2014 Niner RIP 9 (Roval Carbon wheels, Pike)

    Sold:
    Trek Fuel EX8 29er (Rhythm Pro wheels, 2x conversion)

  20. #20
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    Quote Originally Posted by 722ish View Post
    Excuse my language, but damn it! My chain has been dropping constantly and I kept assuming it was just me knocking it out of adjustment. Lbs has done adjustments repeatedly, and I've even switched my ex8 29 to an xt crankset (2x10). The fork is back at fox for another repair so I can't ride it at the moment anyway but I'm going to have them talk to trek at the lbs.
    I'm glad you posted this up, I'll talk to them about it today thanks!

    My rear abp axle kept coming loose, and now the rear hub feels a bit wobbly somehow. Like it has some lateral play even if the axle is cranked down very tightly or even if it's loose. Strange stuff.
    I love the bike, but it sure is fighting me!
    Did you put on a 2x FD when you swapped the crank? My LBS adjusted my 3x SLX derailer to work with my 2x SLX crank but it would drop a chain easily on the trail. I then bought a 2x SLX FD and flipped the switch on the underside of the shifter for a 2x10 set up and it has worked flawless.
    2014 Niner RIP 9 (Roval Carbon wheels, Pike)

    Sold:
    Trek Fuel EX8 29er (Rhythm Pro wheels, 2x conversion)

  21. #21
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    Fuel EX 29er Drivetrain - Chain Roll Off

    Quote Originally Posted by stygz1 View Post
    Did you put on a 2x FD when you swapped the crank? My LBS adjusted my 3x SLX derailer to work with my 2x SLX crank but it would drop a chain easily on the trail. I then bought a 2x SLX FD and flipped the switch on the underside of the shifter for a 2x10 set up and it has worked flawless.
    No, I didn't. I assumed the 2/3 switch was sufficient.
    Thanks for the heads up though, I have a bike that can use the triple front, I will pick up a front and see!
    10 Gary Fisher Cobia - 13 Trek Madone 5.2 - 14 Trek Fuel Ex8

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