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  1. #1
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    Deore disc brakes - break in time/rubbing

    I just bought a bike with deore disc brakes and the rotors rub the calipers. i took the bike in for adjustment and they fixed it. after riding again, they rub again.

    I read in the shimano manual that there's a break in period for disc brakes. I've ridden the bike about 40 miles so far, how long should i wait for the brakes to "break in" before bringing it in for another adjustment?

    any ideas?

  2. #2
    "El Whatever"
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    Deore Mechs or hydros??

    depending on the type the answer will be.

    But... did you get the wheel out?? After remounting the wheel there might be some misalignment due to the QR adjustment.
    Check my Site

  3. #3
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    hydraulics

    Quote Originally Posted by Warp2003
    depending on the type the answer will be.

    But... did you get the wheel out?? After remounting the wheel there might be some misalignment due to the QR adjustment.
    They are hydraulics.

    After i take the wheel off and put it back on. I tried readjusting the quick release but the rotors still rubbed. unless there's some special way to adjust the QR..

  4. #4
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    Try realigning the caliper.

  5. #5
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    how to?

    Quote Originally Posted by pufdup
    Try realigning the caliper.
    is there a link on a how to adjust the caliper. as far as i could tell from shimano's website, it said to loosen the mounting bolts on the caliper, then squeezing the brakes, then tightening. this doesnt sound right though, but what do i know?

  6. #6
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    Quote Originally Posted by garychanchan
    is there a link on a how to adjust the caliper. as far as i could tell from shimano's website, it said to loosen the mounting bolts on the caliper, then squeezing the brakes, then tightening. this doesnt sound right though, but what do i know?
    Yep. that's how you adjust them. Sometimes that works and sometimes it doesn't, but I would still give the brakes a bit more time.

    FWIW, I've got a bike with Shimano Deore discs, and I've had similar problems, especially since I have to remove the front wheel after every ride to transport the bike. I've had the bike around 9 months and I generally don't have rubbing problems anymore, though I do go through a bit of a ritual when I put the wheel on before a ride.

    Here's what I do:

    1. Make sure you're on level ground when you put the wheel on.
    2. Wiggle the wheel a bit...make sure its fully seated in the dropouts
    3. When you tighten the quick release, apply pressure to the fork arch or the handbars to put some weight on the wheel to insure that the wheel is seated and aligned correctly in the dropouts.
    4. The problem does not really seem to be one of alignment, but rather of one piston or the other not reliably retracting far enough when the brakes are released. If I put the wheel on and one pad is still rubbing, what I'll do is loosen the quick release and tilt the wheel in the direction of the rubbing pad, then apply the brakes. This has the effect of resetting the pad's retracted position further out and usually solves the problem. Now, in theory this really this should not work, because it should cause the pad on the other side to move further in and rub on that side. In practice, though, that does not happen. Whatever works.

  7. #7
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    I've had this same problem with these same brakes a bunch.

    Correct me if I'm wrong, but doesn't the 525 design have a piston on one side that moves and a "piston" on the other side that doesn't move? The moving piston bends the rotor ever so slightly so that it is sandwiched in between both pistons.

    I've had my 525's start to rub after a very bumpy & fast downhill where I was on the brakes for most of the time, even through the gnarly braking bumps. (Gotta love the Zoke Z1.) I wonder if the heavy braking forces are actually pushing the caliper over a bit. Hell, I've even had my 525's mysteriously start rubbing the caliper body on the rotor. Talk about squeak! Realigning the caliper (as described by garychanchan) fixes the problem, but it eventually comes back, generally after a haaaard downhill.

    After re-aligning many, many times. I've upgraded to XT 4-pistons (but haven't installed them yet.)

  8. #8
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    Quote Originally Posted by phUnk
    I've had this same problem with these same brakes a bunch.

    Correct me if I'm wrong, but doesn't the 525 design have a piston on one side that moves and a "piston" on the other side that doesn't move? The moving piston bends the rotor ever so slightly so that it is sandwiched in between both pistons.
    I think mechanicals work this way, but on the hydraulic 525's, I'm pretty sure both pistons move.

  9. #9
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    I have the same brakes

    Mine rub after I've been braking downhill for a while. My LBS said the hydro fluid heats up, expands, and then pushes the pads against the rotors. When things cool down, the rubbing stops. But this doesn't happen on my motorcycle, which has brakes that probably work just as hard if not harder than my mountain bike. Is this normal?
    我的镀铬光泽的冰柱一样,我骑在镇附近在我的低骑手自行车

  10. #10
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    Mine occasionally do that, but only on a very long, steep, twisty asphalt downhill that leads to the trails where I sometimes ride.

    My understanding is that in an open system, the pistons should not be able to move because of heat in the fluid. I'm again more inclined to believe that it's the pistons simply not reliably returning to the proper point, possibly because the heat is expanding or slightly warping the mechanical parts and causing a bit of binding.

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