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  1. #1
    mtbr member
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    Jul 2010

    Trek 3900, Promax mechanical disc rubing against brake caliper

    I have a 2009 Trek 3900 with the stock Promax mechanical disc brakes. I was rotating the front wheel today inspecting the bike and heard a faint squeling sound. After closer inspection, it looks like the disc is slightly warped and chaffing against the brake caliper upon rotation. It's not a bad/loud sound, but annoying all the same. Is this normal? Just let it be or is there a quick fix to remedy this situation? Trying to tackle bike issues myself first as opposed to bringing the bike rite in to the LBS for inspection.

  2. #2
    AZ is offline
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    Apr 2009
    Its normal for that to happen, it can be fixed.In one spot or rubbing all the time? If its in one spot, just true the rotor ( bend it straight ) with a couple of adjustable wrenches or a rotor truing tool. If it rubs all the time, recenter the caliper. You can do that by loosening the mounting bolts, gently applying the brake and tightening the mounting bolts. Good luck.

  3. #3
    mtbr member
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    Jul 2010
    I think it's rubbing in one spot. Is this something I need to tackle asap or can I address this at the end of the season if I wanted by LBS to take care of it?

  4. #4
    mtbr member
    Join Date
    Jun 2007
    If the rotor is touching the caliper (metal on metal), you need to fix it now. No problem waiting if it's just touching the pad.

    You may be able to true it without any tools, too. Identify the high spot and push it in with your thumbs, using your fingers to keep the rest of the rotor from bending. Then clean it with some isopropyl alcohol to remove the skin oil.

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