|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Frame/wheel flex and disc brake problem
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) |
Ads |
#2
|
|||
|
|||
Frame/wheel flex and disc brake problem
Caspar Lugtmeier & Eva Skotarczak wrote: 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) The first thing I would look for is a broken axle. If you have enough frame flex to cause the drag, I would look very carefully for cracks. Miles |
#3
|
|||
|
|||
Frame/wheel flex and disc brake problem
Yes, that's what I tought too, I have already checked that (and the
tightness of the freehub bolt). Thanks, Caspar "miles todd" schreef in bericht ... Caspar Lugtmeier & Eva Skotarczak wrote: 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) The first thing I would look for is a broken axle. If you have enough frame flex to cause the drag, I would look very carefully for cracks. Miles |
#4
|
|||
|
|||
Frame/wheel flex and disc brake problem
4) FSR rear end bearngs have play in them, replace. (688RS)
That's a good one. If it's not the wheel/skewer I will do this. Thanks, Caspar |
#5
|
|||
|
|||
Frame/wheel flex and disc brake problem
"Caspar Lugtmeier & Eva Skotarczak" wrote in message
... snip 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 know that the manual probably states that 0.2-0.4mm is the recommended clearance. In reality and in practice I have found it to be more like 0.5mm. I think that 0.2mm is wishful thinking. -- Westie |
#6
|
|||
|
|||
Frame/wheel flex and disc brake problem
The disc brakes are Magura Louise's, model 2004. And no, it is not wishful
thinking but measured... (using a tool). I would much more prefer a distance of 0.5 mm !! (obviously) Caspar "Westie" schreef in bericht ... "Caspar Lugtmeier & Eva Skotarczak" wrote in message ... snip 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 know that the manual probably states that 0.2-0.4mm is the recommended clearance. In reality and in practice I have found it to be more like 0.5mm. I think that 0.2mm is wishful thinking. -- Westie |
Thread Tools | |
Display Modes | |
|
|