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  1. #1
    mtbr member
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    Weight Induced Derailleur issues?

    I was wondering if anyone else has this problem. I will bring my bike in, the mechanic will get the derailleurs all tuned up and running nice, but when I get on the bike they rub. Typically the front, but sometimes the symptoms happen in the rear derailleur as well. I've gone to different mechanics and I know they are doing a great job...I'm convinced my weight on the bike is torquing the frame and causing the misalignment. Short of getting on the bike, riding, getting off, adjusting, riding again, repeat, repeat, repeat...anybody have some novel ideas? I was thinking about using a rachett strap between the top tune and bottom bracket so the frame is under stress while I'm adjusting the deraileur. Mt LBS had recommend a "stiffer derailleur", but I didn't know derailleurs came in different "stiffnesses"?

    I ride a new Trek Hard tail. 6'4, 215 lbs.

  2. #2
    Fat boy Mod Moderator
    Reputation: donalson's Avatar
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    does it happen when you are just spinning along or only when you are realy crankin?

    sounds about right though... the frame and/or crank is flexing...

    what model trek specificly?
    - Surly Disc trucker
    - '82 trek 560 roadie

  3. #3
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    I'd recommend finding a different shop. It doesn't sound like they are doing as good a job as you think, and there is no such thing as a "stiffer derailleur." I'd guess they are either yanking your chain (because "stiffer" equals "better" in bike-advertising speak), or are profoundly stupid.

    On top of all that, you aren't that heavy. Unless your frame is damaged, I wouldn't expect much flex-induced rubbing unless you are cross chained and torquing really hard.

    Adjusting a front derailleur has stumped many a shop mechanic, that would be my bet for your problem.

  4. #4
    Fat boy Mod Moderator
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    oh ya I forgot to mention that...

    while there are stiffer front D's... it won't do much except when shifting... and IMHO is mostly just marketing...

    but joules does make a good point that it needs tweaked... perhaps spend some time tweaking it yourself?
    http://www.parktool.com/repair/readhowto.asp?id=75

    - Surly Disc trucker
    - '82 trek 560 roadie

  5. #5
    mtbr member
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    Typically, it will work fine (after I've gotten it back from the shop). But sometime during the first ride or so, it'll start rubbing. Typically I commute, so I'm not really cranking on the pedals, its fire road stuff, with some climbs out of washes, etc. So not street riding, but nothing too crazy.

    I'm riding a 2008 Trek 6700. My theory is that due to my 6'4 height, I'm riding the largest frame possible (21.5?). I think that magnifies the stresses on the frame.

    I fully suspect I will have to take this challenge on myself. I can't see myself saying to my LBS to "adjust for the torque of my weight." But I'm not very good adjusting my own derailleurs at this point, so I'm kind of stuck.

    I have wondered if a Full Suspension would alleviate the torque issue, but since I just bought this bike last year, buying a FS isn't in the near future.

    I definitely see the torque issue with my disc brakes as well.

  6. #6
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    Quote Originally Posted by donalson
    ... perhaps spend some time tweaking it yourself?
    http://www.parktool.com/repair/readhowto.asp?id=75
    Yep. I spend a bunch of time on the Park Tool site trying to learn the black art of derailleur and hydraulic disc brake adjustment. Love their site....but haven't been real successful mastering the skills yet. :-(

  7. #7
    Fat boy Mod Moderator
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    big alu tubes on that frame... i seriously doubt it has anything to do with frame flex (i can see it flexing on my steel frames but only a little... a bit more on my old trek road bike with biddy tubes... but alu won't flex near as much... also... a larger frame would flex MORE not less

    I see you have a deore front D... do no issue there... just heavier then the higher end stuff realy...

    i'm going to go with the incorrectly adjusted D... when it the ring and see where it's rubbing... starts making noise look down and watch... is it doing it in the middle or big ring?

    getting the front D installed/adjusted right is a touchy one... as someone said on MTBR... it realy is a black magic type thing... trial and error..
    - Surly Disc trucker
    - '82 trek 560 roadie

  8. #8
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    Mine does it as well. It doesnt rub when riding normal, but when really cranking it will rub. I believe its the cheap ISOflow cranks that came on mine.

  9. #9
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    I weigh 300lbs and I rode a Trek 4300 for a good long time. Donalson is right, Trek builds those frames bombproof because they sell a zillion of them and don't want to hear about broken frames, no matter who is riding them.

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