I bought a new bike that has mechanical disc brakes. They were squeaking really hard. I tried aligning the caliper. Now the squeaking noise is gone form the front brake, but not from the back brake. I noticed that the brake in the back has less space between the disc and the brake pads, but that shouldn't be a problem. The brake pads are new and so are the discs, and I cleaned everything. What should I do?
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How new are the pads? Do they come from the original owner or are they yours? They may be contaminated.– Vladimir F Героям славаCommented Jul 23, 2020 at 13:32
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Squeaking when brakes not applied and just riding along or when brakes applied?– Argenti ApparatusCommented Jul 23, 2020 at 14:09
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What did you clean them with? My disc brakes squeak like buggery when they’re wet but it soon disappears once the pads have dried– Dan KCommented Jul 23, 2020 at 14:32
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1I've found that squeaking when the brakes are applied is common with new pads, and usually quiets down after a few rides. If they're squeaking when the brakes aren't applied, that's a different issue, and you might need to true your rotors (yes, sometimes even brand new rotors can be out of true).– MikeyCCommented Jul 23, 2020 at 17:28
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I have solved squeaky disk stoppage by taking the rotors off and sanding them with some 800 grit paper in a random fashion. When disk brakes were introduced, I liked the concept and had a couple disk equipped bikes. I usually had squeaky brakes. disk brake pads are not mounted firmly to the caliper, but on a spring loaded pivot, so they will tend to vibrate against the rotors. You could mess around with different pad compounds, but they will probably squeak on damp rides, etc.– bradlyCommented Jul 23, 2020 at 18:22
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1 Answer
Ugh! Bicycle disc brakes are not without their weaknesses. The frequent attention and adjustment they require due to noise or pad rub is particularly irksome to me, closely followed by the system's ridiculous intolerance to pad contamination (really? That sort of flaw considering the environment they're to be used in?), the recommended "fix" being pad replacement.
Park Tool's mechanical disc brake tutorial is one of the best discussions regarding mechanical disc brake set-up, alignment and trouble shooting I've seen. The best advice I can give you is to watch the video and/or go thru the text.
A couple pointers: 1)often times when there is noise or rubbing that won't go away after resetting the caliper alignment, if you re-do the alignment loosening only one of the caliper fixing bolts, it helps to quiet the problem. 2) a disc brake rotor needs to be trued more often than people realize. Brake noise that's refractory to resetting the caliper almost always has rotor issues at it's heart. 3) the value and importance of bedding in new pads and rotors is often understated. Learn how to do it correctly. AND DO IT! 4)don't use the brake lever's barrel adjuster to tweak the pad distance in a mech. disc system.. These are only for countering cable stretch. 5) be mindful of the contamination issue and keep oils, greases and your fingers away from the pads and rotors. Keep rubbing alcohol on hand and use it to clean pads and rotors often. Use a clean rag for this.
