Why do bicycle brakes squeak?

Question

My back brakes squeak really loudly when they are used, but my front ones don't. The bike shop owner said nothing could be done about the noise, but he didn't explain why it happens.

Answer 1

i can actually answer your question: it from the pads being toed in too far. the front end of the pad is coming into contact with the rim before the rear of the pad and thus you hear a squeeking noise. this can be fixed by a simple pad adjustment most of the time. the oad must be almost parallel to the rim, with the front a little closer to the rim than the back, but very slightly. also sand down the braking surface of the rim with a very fine grit sandpaper. dont scrub the rim, just lightly rub it, then wipe off the residue with a rag and a little rubbing alcohol.

if that doesnt work then get new pads. a decent set costs about $15 and will last quite a while.

Answer 2

The reason for the squeak, or squeal is that the blocks on the point of contact on the rim vibrate, or oscillate, against the rim - this oscillation causes a noise in the same way that a violin that is played by a bow will oscillate to produce a noise. There is only one way to remove the squeak, and it has nothing to do with composition of the rim, or the brake blocks or anything else like that - it is purely the satisfactory mating of the two surfaces, and the ensurance that absolutely nothing within the brake is able to move along the axis that the rim is travelling, so the caliper is tight, the blocks in the shoes are tight, the wheel rim has no 'play' at the outer edge caused by 'play' in the hub bearing, there is a grip washer between the caliper and the frame on the caliper side, and a spring washer on the nut side of the caliper. Also, try taking a bit of sandpaper to the surface of the brake block, because if you have suffered this for a long time - the block might now have a 'shiny' appearance on the surface that mates with the rim - like a car brake pad does after it has got very, very hot if you have ever seen one. Don't be fooled into buying loads of new stuff - you don't really need it - unless, like me you are a bike head - who buys loads of kit for no real reason....

Answer 3

Do not pour oil on them!!! That will totally ruin your brakes especially disk brakes. The best option would be to take it to your local bicycle dealer and have them install new brakes and pads and have a technician take a look and see what the cause of the squeaking is. It is probably excessive wear and tear from hard riding or it could be something other than the brakes completely. If it turns out to be the brakes and pads, pick out some Hayes or Shimano brakes, they are very reliable and don't break easily. You can also purchase a warranty just in case you ever need more repairs. Just don't oil the brakes! :)

Answer 4

I agree with i_love_it above except he didn't give you a fix.

Most times squealing is caused either by the brake pad hitting the rim flat or by the rear of the pad hitting the rim first.

Usually, this is easily adjusted out by making sure that the leading edge of the pad hits the rim before the rear edge. On cantilever and linear pull (V) brakes it is a simple matter to readjust the angle by loosening the pad and repositioning. On sidepull brakes as used for road bikes the brake arm usually needs to be "tweaked" and twisted a bit to allow this to happen... this is a very common thing for professional mechs to do to stop the squealing.

Answer 5

I often spend my half an hour to read this blog's posts daily along with a mug of coffee.

Answer 6

they dont squeak all the time for me. maybe your just in a real dry climate. or maybe you got some low quality brakes.

Answer 7

do you have quality brake pads? Have you looked at the pads- do they have little metal filaments in them?
if so, can you dig them out carefully with a knife? this may help ease the noise.

Answer 8

Friction of rubber on metal.

Answer 9

The more harder you brake there is more friction so it makes a noise

Answer 10

Friction. What kind of question is this, you some one that thinks you earn points for questions? O My God..... I have to say this is the worst question 2 date.