Frame/wheel flex and disc brake problem

Discussion in 'Mountain Bikes' started by Christophe, Jan 27, 2004.

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  1. Christophe

    Christophe Guest

    Hi all,

    This is the first time I post here, I'm Christophe 27 year old, riding a 03 Specialized FSR disc in
    the french alps.

    I post this e-mail cos I'm experiencing exactly the same trouble as yours with exactly the same bike
    and component setup.

    My dealer already exchanged the frame and wheel, and got the deore disc brake checked by shimano
    (no issue there). I can reproduce the issue on my wife's FSR also, with my wheel and brake
    mounted on it.

    I currently do no what to do anymore, because this looks like a "built-in feature" of the
    stumpjumper FSR to have that kind of flex.

    Did you manage to fix this by changing a skewer or getting a better hub than the deore disc?

    Question for all, do you experience on your own full suspension bike any lateral movement of the
    disc when seated on the bike?

    Thank!

    Christophe

    Message 1 in thread From: Caspar Lugtmeier & Eva Skotarczak ([email protected]) Subject:
    Frame/wheel flex and disc brake problem

    View this article only Newsgroups: alt.mountain-bike Date: 2003-11-10 03:04:05 PST

    Hello,

    I have some problems with my rear disc brake: When the rear is not weighted, the wheel+rotor spins
    freely and the distance between pads and rotor is evenly ditributed. However, when I sit on my bike
    it touches the inside pad (note that I weigh 68 kg....).

    At first it was driving me crazy (re-adjusting the caliper+pads numerous times), but now I have
    identified the problem, and am very close to finding the cause:
    1) frame flex (Specialized Stumpjumper FSR comp 2003)
    2) wheel flex (Shimano deore disc+Mavic X221 rims, not so good anyway, looking for upgrade with DT
    swiss component wheels)
    3) skewer flex? (Shimano deore, already ordered XTR skewers)

    Note that the distance the rotor moves (when you put weight on the bike) is very small (+/- 0.2 mm)
    but deadly when using discs. I hope the cause can be found in 2) and 3) (will try with some other
    wheels at the LBS) but I am afraid that it might be cause nr 1) When the rear wheel is weighted it
    should bend in a way that the rotor touches the outer pad (if that was the cause) right?

    Anyway, have some of you experienced similar problems?

    Thanks, Caspar

    (PS: now I have the pads adjusted so that they are free when I sit on the bike.... and drag when you
    just spin the wheel)
     
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