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Thread: Disc Grinding

  1. #1
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    Disc Grinding

    I am an ultra newb and have no previous biking experience from my younger life so I am still figuring out a lot of this stuff. I am 6'9" 295lbs and own a 2013 Trek Cobia that is mostly stock except for saddle and handlebars. I am not doing anything extreme at all, I'm near Atlanta so mostly it's just basic trail riding (singletrack). I have fallen a few times but nothing major, but I keep having issues with my disc brakes rubbing the pads (is pads right?). So I am not sure if this is caused by something I can swap out or upgrade. I realize there are a million reasons that can probably make the discs rub against the pads, but I just want to know if this is a common issue with clydes.

    Please let me know what else you guys need to know?

  2. #2
    R.I.P. DogFriend
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    It is possible to bend the rotor back to being true. You can use a specially designed tool, or a Crescent wrench works OK too. It takes a bit of experience to learn how much force it takes to bend the rotor enough, but not too much, but isn't terribly difficult. I have seen several new rotors that were not true from the get-go. I would try to true it yourself before buying a new rotor.


  3. #3
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    I took it to my LBS for the rear rotor last time and they trued it up, and after the second ride since then my front rotor is now rubbing. I just don't want this to be a every two ride thing if its something I can upgrade.

  4. #4
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    You say your brakes are rubbing. Are they rubbing constantly? Or is it like the rotor is warped?
    If it is a constant, the LBS should be able to adjust it pretty quickly and get it right the first time.
    If you are warping the rotors, I'd look at a better brake rotor or braking system. I am not sure, but many times stock items on bikes are not always as good as they should, or could be.
    If the rubbing is intermittent (warping) I'd also wonder are the wheels going out of true as well? If this is the case a stronger wheelset may be desired. The Cobia is not a hack bike in any way, but clydes are naturally harder on bikes just due to being a clyde!
    And you might be surprised how little it would take to warp a rotor. I have had some pretty dramatic crashes where nothing was damaged (except me) and some really wimpy spills that have broken things. All depends on what hits when and what hits what.
    Remember when we were kids and our Mom's said we could not play in the mud? I'm making up for it now!!

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    Have you just got some crap between the pads and the disc? Did you knock the caliper? Is the front wheel seated in the fork properly and the skewer secured properly?

    Lots of things can happen, none of them clyde-related.

  6. #6
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    Quote Originally Posted by TooTallUK View Post
    Have you just got some crap between the pads and the disc? Did you knock the caliper? Is the front wheel seated in the fork properly and the skewer secured properly?

    Lots of things can happen, none of them clyde-related.
    I second that! If you're riding off road look for some kind of trash in between the pads and rotor? Or if you are removing the wheels for any reason between rides make sure they are centered before locking the skewers down. Other than that, check to make sure the rotors and calipers are tightened/centered properly and give it some time. I have found that "new" brakes need to be broken in a bit before all of the noise goes away. Some people have even beveled the edges of the pads to help fix the noise. You could also look into larger rotors which tend to stay cooler due to the increased braking surface? It looks like your fork (recon silver?) can fit a rotor up to 210mm. Due to your size, it's possible you are overheating the rotors which could lead to warping? My bike came stock with 180f/160r rotors and it seemed to stop pretty good but I recently bought some new xt m785 brakes and larger 203f/180r rotors and it is night and day! Sorry for rambling on there but let us know what you find!

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