I recently bought a fat tire bike and the rear disc brake has developed an annoying squeak when applied. Does anyone have a remedy that would take care of it? I've been told it's debris build-up but I've only ridden it on concrete and asphalt paths so far. Sprayed and cleaned the rotor with rubbing alcohol and that only worked for about the first 3 times the brake was used. Now back to squeaking again. Any advice would be greatly appreciated.
This is not an uncommon problem, especially for fat bikes. It would appear you have mechanical disc brakes, so there is a couple of things you can do. the easiest simplest thing to do is get new pads and rotors. but that gets pricey, and good luck finding rotors in stock. if you want to do the fixes yourself then I can recommend what I would do if it were a bike brought to me. The pads and the brakes go together, if one is contaminated the other is. by the sound of it, the main thing on yours is the pads, because you tried to clean the rotor and it helped a bit. so in this case, take out the pads, get some sandpaper, not too rough, but not too smooth. I usually aim for 100-150 grit, some people may disagree but this is what I usually use. spray the pads off a bit with isopropyl alcohol, to get some of that first gross layer off. then spray an area of the sandpaper with the alcohol, and begin sanding down the pads, moving in little circles. you can do this until they look pretty much their original color. take note of the color of the pads when you started, and when you finish sanding, in most cases the pads will end up being a silvery-gold kind of color when done. now you can put the pads back on the bike. DO NOT TOUCH THE PAD SURFACE WITH YOUR BARE HANDS, the oils will leach onto the pads and make them squeaky again. now on to the rotor, take it off of the bike- this is the easiest way. place a paper towel down on a table, put the rotor on it, spray with alcohol, and scrub that bad boy real hard with another paper towel. repeat for the other side. If you hold the rotor up to the light, it may be reflective, that's fine, but as long as you don't see a rainbow-like glaze over it in the light then you should be good. put everything back on the bike making sure not to touch them with your hands too much - just use gloves - and you should be good.
Hope this helps!
Hi @lpmover!
Here is another reply that supports @ChaseCal post, written by our community member Rob via Facebook:
"Take the pads out and clean them also, they will be contaminated, so will just contaminate the rotors again. Sand down to remove glare, then clean with rubbing alcohol/nail polish remover, and clean the rotors with a cloth again before refitting pads."
Try cleaning the rotors first. This is often the most common reason for squeaking.
You can use high proof alcohol. Scrub them good. Also try to get a Q Tip in there and give the pads a good scrub.
A film develops on them both from dirt and debris, which causes loss of friction in the engagement process, producing squeaking.
The next troubleshoot is to tighten the spacing on the caliper pistons. As the pads wear down, distance forms and develops slack in the engagement of the caliper. This leads to a weak engagement which causes squeaking. There is a bolt on the side that is used to control the spacing on one of the pistons. You'll need to tighten the bolt very cautiously.
You may have to realign your calipers in this process. Totally untightening them, positioning them center, then retightening the mounting bolts to the frame. You may also need to true the rotors.
This will be to troubleshoot any rub experienced with the caliper pad tightening.
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