Rim damage from brakes?

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  • 08-23-2013
    wsommariva
    Rim damage from brakes?
    Hi everyone,

    I have a 2009 Trek Navigator 2.0. 2.0 inch tires.

    I thought I'd replace the rubber brake pads before my LBS did.

    Front rim now has a groove in it. Don't think it came that way. Would the brake pad have done it and can I fix it?
  • 08-23-2013
    Cyclo-phile
    If the groove is roughly halfway up the face of the brake track, follows the full circumference, and is consistent in profile, then you're looking at a wear indicator that has been machined into the brake track. If it does not meet those criteria, then check your pads for debris, pick it out if necessary, and continue to enjoy riding your bike.
  • 08-23-2013
    tlg
    Yes pads absolutely can (and eventually will) wear your rim. Especially if you get stones and debris stuck in them. Essentially making them sandpaper.

    It's good to regularly inspect, clean, and replace your pads.
  • 08-23-2013
    wim
    Something hard stuck in the brake pad could certainly put a groove into the rim. But it's no big deal, and I wouldn't even consider it "damage."

    Rims can and do wear out from braking The rim material at the braking surfaces gets thinnner and thinner and eventually, the brake track cracks and then separates from the rest of the rim. With most rims, the early warning sign of this is the brake track becoming concave. But to get to that point, it normally takes many miles of heavy braking in sloppy weather with no post-ride cleaning ever.
  • 08-23-2013
    looigi
    FWIW: In my most recent experience, it took 11k miles to wear a rear rim to the limit of the wear indicator dimples, almost all of that on dry pavement.
  • 08-23-2013
    tlg
    Quote:

    Originally Posted by looigi View Post
    FWIW: In my most recent experience, it took 11k miles to wear a rear rim to the limit of the wear indicator dimples, almost all of that on dry pavement.

    Front or rear rim?
  • 08-23-2013
    wsommariva
    Thanks everyone. Good to know it's normal wear and tear. I just replaced the pads.
  • 08-24-2013
    Pitts Pilot
    It is normal wear tear. But it's important that you understand that the walls of your rim are getting thinner over time and eventually the pressure in your tire can/will cause the side wall of your rim to blow out. This normal wear and tear can be reduced by keeping your brake pads free of debris. Many rims now have some type of indicator to help you know when it's getting too thin. (Such as a hole drilled from the inside toward the outside, but not all the way through. When your rims get thin enough, the hole appears on the outside.) I ride mostly on steep roads and often in the rain. Rims only last me 2 years and probably not more than 6-8 thousand miles.
  • 08-24-2013
    MikeWMass
    I bought a used tandem from CL. It was one step up from a BSO, has 26" tires, and had been sitting in a barn (literally!) for several years. I cleaned it up, repacked all the bearings, and bought some 100 PSI smooth tires. When I pumped up the front, the tire blew off. I thought I hadn't seated the bead, but the rim was actually bent. It turns out there was a groove in one side, must have had a pebble or something in the pad and wore enough that it blew with the pressure. The moral of the story is, if it is not part of the design of the rim, it COULD be a problem.
  • 08-25-2013
    looigi
    Quote:

    Originally Posted by tlg View Post
    Front or rear rim?

    Rear. They always wear out faster than fronts, and I brake mostly with the front. My theory is the rear gets more junk on rims and pads thrown up by the front tire.
  • 08-26-2013
    tlg
    Quote:

    Originally Posted by looigi View Post
    Rear. They always wear out faster than fronts, and I brake mostly with the front. My theory is the rear gets more junk on rims and pads thrown up by the front tire.

    Maybe you should rotate your rims. :biggrin5:

    Probably a good theory.
  • 08-26-2013
    wim
    Quote:

    Originally Posted by tlg View Post
    Maybe you should rotate your rims.

    Or wear fenders when it rains. Only takes an hour or two to put them on. :-)

    Was going to delete "wear" and put "use," but this is too good of an image to get rid of.
  • 08-26-2013
    looigi
    Quote:

    Originally Posted by wim View Post
    Or wear fenders when it rains. Only takes an hour or two to put them on. :-)

    Was going to delete "wear" and put "use," but this is too good of an image to get rid of.

    Fenders do nothing for rim wear and IMO may actually exacerbate it because it keeps all the road grit dripping back on the on the tires, wheels and brakes. It sure does on my rain bike, which has full fenders.

    And of course the suggestion to rotate the rims was tongue in cheek. Many have a different number of holes and some have different drilling angles f/r. In my case, my rear rim is not only rear specific, but has a left and right side which differ by the angle at which the DS and NDS spoke holes are drilled.
  • 08-26-2013
    wim
    Quote:

    Originally Posted by looigi View Post
    Rear. They always wear out faster than fronts, and I brake mostly with the front. My theory is the rear gets more junk on rims and pads thrown up by the front tire.

    My tongue-in-cheek fender idea was based on your correct notion that the rear gets more junk on rims and pads thrown up by the front tire. It follows that with a full fender around the front tire, the rear wouldn't get as much junk on rims and pads thrown up by the front tire. But don't take any of this too seriously.
  • 08-26-2013
    looigi
    Quote:

    Originally Posted by wim View Post
    My tongue-in-cheek fender idea was based on your correct notion that the rear gets more junk on rims and pads thrown up by the front tire. It follows that with a full fender around the front tire, the rear wouldn't get as much junk on rims and pads thrown up by the front tire. But don't take any of this too seriously.

    A full fender in the front would have to go all the way down to the road to prevent stuff thrown up from the front wheel from hitting the rear rim. Remember, stuff thrown off a rotating wheel travels tangentially to the wheel, not radially.