I've tried sanding them down just a bit, cleaning the brake surface on the wheels, and this does stop them from squealing for a day or two, but it always comes back. I'm using Kool-stop pads if it matters.

  • Are these rim brakes? Commented Aug 26, 2010 at 3:22
  • The Kool-Stop brand pad (as the poster mentioned) are rim brakes. Commented Aug 26, 2010 at 16:03
  • Correct, Rim brakes. Thanks for the answers folks, I got what I needed. Commented Aug 26, 2010 at 16:21
  • I'm havein the same problem. I have Aluminum Shimano DEore Wheels and Promax Alloy Pads. it started squealing before 2 hours :O it rained night before so i think it is cause of moisture and water on my rim. i'll have to clean it up and i'll reply again if it doesent work.
    – user5868
    Commented Jan 10, 2013 at 11:56
  • Kool-Stop brand pads for discs also exist. But I doubt anyone would sand them, and while a disc could technically be described as a "brake surface on the wheels", that's also unlikely.
    – armb
    Commented Jul 17, 2013 at 9:18

4 Answers 4


There are a few causes for brake 'squealing':

  1. New pads. After a bit of wear (or sandpapering), the squealing will stop.
  2. Misalignment. As some others have mentioned, misalignment may cause squealing (although it would be reduced with some wear). Check out Sheldon Brown's tips for alignment suggestions.
  3. Oil or water on the rim. Either of these substances, even in small portions, combined with dirt or debris on the rim can create squealing. Wipe the rims thoroughly on the braking surface, as well as the pads, with a dry cloth.
  4. Incompatible rims/pads. No one else has mentioned this, but this is often the most common cause. Rims are generally made from one of two materials: steel or alloy. (You can tell the difference by seeing if a magnet will attract (steel) or not (alloy)). Incidentally, brake pads are made of specific compounds to work on one or the other. Often, using pads designed for alloy rims (like most Kool-Stops) will squeal if used on steel (which I'm guessing you have).

Brakes have to be toed in. What that means is that the front of the brake pad has to touch the rim before the back of the brake pad. It does not have to be an extreme variance but it will make a world of difference when properly adjusted.

Hopefully you have aluminum rims. I have had the misfortune of working on some bikes with steel rims from which I could not remove the squealing.


Take a look at the adjustment of your pads. Sheldon Brown has a great article on how to do this.


The major cause of squealing is oil on your rotors/pads. Could be just from touching or leaking braking fluid.

Use rubbing alcohol on pads (after sanding) and on rotors. That's how I fixed mine a year ago and never heard a squeal again.

  • Kool-stop pads are rim brakes. Don't think the disc fixes will work too well.
    – Jack M.
    Commented Aug 26, 2010 at 0:41
  • why do you say oil is the major cause? almost all breaks that squeal can be fixed by toeing in except in the less common cases when sanding is required (this may be partly related to oily crud) or the brake/rim combo is bad. Commented Nov 30, 2010 at 13:16

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