Frame/wheel flex and disc brake problem
 

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 )
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)