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  1. #1
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    Brake Rotors Touching Pads at Random Intervals

    Hi everyone,

    I was having with my new Avid Elixir 4s rotors constantly rubbing the pads for the longest time, and solved it by release some brake fluid. Now, the rotors don't touch the pads when pedaling on a bicycle stand. However, when I bring it out for a test ride and riding it at higher speeds, the front rotors would rub the pads until I slow down. The rear brake would just rub at random intervals (rarely but happens still), regardless of speed.

    Is there anything else I can do? Or is this just something I have to live with if I wanted hydraulic brakes?

  2. #2
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    Check that your wheels are seated properly in their dropouts, and check the tension/tightness of your skewers. On the front, it is possible that you are getting some fork flex causing a bit of rub. If your brakes (front and rear) are working with enough power to stop you, then a small bit of rub shouldn't be an issue.

  3. #3
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    ^^^^ Thank you, i've double checked and they seem to be in the correct setting.

    [b]The funny thing is, the front only rubs at a certain speed, and once it gets past above/below that speed, the rubbing subsides.

    Ex:
    0-10 mph --- no rub
    11-15 ------- rub
    16+ --------- no rub

    This sort of rules out the fact that the frame and fork moving at high speeds makes them rub... Since it should continue to rub at 16+ mph instead of stopping altogether....

  4. #4
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    This reminds me of the most suspenseful movie ever made, The Wages of Fear. The story follows a man stuck in an isolated town where the only way in or out is by plane, and it's apparently an expensive ticket in a town where no jobs are to be had with the exception of driving a truck load of nitro-glycerine to the blasting/ construction site. The drivers' need to go either above or below a specific speed for the bumpy road to avoid rattling the nitro or.....KABOOM! Perhaps this is what you are experiencing?

    Seriously though, your rotor is slightly out of true or perhaps the pads aren't seated correctly. The offensive rub is short so it's not too out of true. When you're going faster the rub is shorter since the rotor spins faster, when slow it's drawn out a bit and doesn't draw your attention. You could push the bike backwards to see if grabs the rotor more noticeably. If it's the pads, does the rub go away if you brake hard and release? Perhaps that will set the pads until they rattle looser again. If it really bugs you take it to the LBS. Vibrational wavelengths will change with speed and terrain, which may account for your observations. As has been stated above, a little rub is not a big issue. Rattling though.... huge.
    No fuss with the MUSS

  5. #5
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    Do the brakes rub when the wheels are spun stationary? (Bike in the bike stand or simmilar)

    I cant think of a reason that would be speed related.

  6. #6
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    Quote Originally Posted by B.BL View Post
    Do the brakes rub when the wheels are spun stationary? (Bike in the bike stand or simmilar)

    I cant think of a reason that would be speed related.
    It did rub when stationary, then I brought it to a LBS to get it trued and now it doesn't rub at all. Only rubs at a certain speed and once past above/below that speed, the rub stops.

  7. #7
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    Hey Guys,

    I know this thread is a few months old but I wanted to add that I experience the exact same thing.

    I do all my own bike maintenance and this speed related brake noise is the only thing I can't seem to get rid of. I've just put up with it through the seasons but I try little things every time I tune it.

    I'm running a 08 Fox Talas fork with Avid BB7s and 203mm (8") G3 Cleansweep rotors. The rotors are mounted on a set of Cane Creek Zonos wheels and hubs, secured in place with Shimano XT (internal cam) QRs.

    The rear is fine even with the 203mm rotor (yes, I know I don't need a 203 in the rear, but I like the look!) as the hard tail GT Avalanche frame with the internal cam QR makes everything stiff. Problem is with the front where, just like you BobaX, if I get to about 20km/h (13mph) the noise starts and if I get above or below that, it stops.

    When I mount my bike to work on it, I can spin the wheel and nothing rubs and I can see the gap between the rotor and pads. There is some wave to the rotor that I try and work out, but it's impossible to get true. I'm pretty sure it comes down to how my fork/hub flexes when I'm pedaling at those speeds. My cadence/body motion is such that it's causing the most continuous flex. One other thought I had is at that particular speed, I hit the resonance frequency that causes the rotor to oscillate.

    Like I said, I've just been dealing with the noise as I'm not always going that those speeds because the alternative is to throw a lot more money at it to get a stiffer front end.

  8. #8
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    you may also want to check to see if you have any play in the front/rear hub, which could also contribute to what you are experiencing. While the bike is stationary, take hold of the wheel and try to move laterally side to side (90 degrees from the direction of rotation). Ideally, there should be no play, but a small amount is usually the case. The play may be caused by the hub needing to be tightened up a little. Well, not necessarily the hub, but the outer axle bolts. You don't want these too tight or you will restrict the wheel from turning. Could also be that the bearings (usually sealed) are worn. If you have excessive play in the wheel bearing, all the brake adjustment in the world is not going to solve the problem.
    2008 Trek Fuel EX 8

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