Disc brakes sound

[Catrin]

There is something odd with my Jamis, and I don't know enough about disc brakes to know if this indicates a problem...

This doesn't happen when I am riding or braking, it happens only when the bike is still and I am holding it while unlocking my door, something like that. The fork moves a little and there is a very high pitched metallic squeel. It isn't loud, but VERY high pitched. I doubt they could hear it at the LBS because there is so many other sounds that would likely mask it.

Oddly enough the sound continues for a few seconds after I stop the bike from moving - and it only happens when the fork makes very slight movements - typically when I've tipped the bike sideways rather than forward movement. Once I actually roll the bike forward for real movement it doesn't happen.

I hope this description makes sense, it is difficult to describe. Any thoughts on what might cause this? I am tempted to ignore it, but I don't know enough about discs to know if this is wise...

[Becky]

My disc brakes squeal a little when I move the wheel backwards. I'm guessing that I have a brake rotor that's slightly out of true, but I don't worry about it, since it doesn't occur while I'm riding. But all the important bits are tight, and I know that my brakes are properly bled.

Are your fork etc., rotor, and brake caliper tight? Never hurts to double-check...especially on a new bike.

[Aggie_Ama]

My DH and I have both had the problem on our disc brakes, usually it is the rotor has been slightly knocked out of true. Pretty simple fix for the LBS but I don't attempt it myself. I have a thing about not working on my own brakes, they have too important of a job! The other thing I had was a problem with was non-organic brake pads, they were just noisy and I switched them out at the recommendation of my shop.

[Becky]

Truing rotors is a pain in the *bleep*, even with shop tools. Been there, done that.

[lph]

Is it when the fork or the wheel is moving (compared to the rest of the bike)?

Probably the brakes, but a squeal when the fork is moving relative to the bike indicates something in the headset.

[Catrin]

I will take it today. It just had the new bike tuneup two weeks ago, but yesterday was my first chance to take it out. All I did yesterday was practice riding in circles, figure 8s and several of the body positions they taught me so I doubt I did anything to it...

I could be wrong, but I think it was when the fork was moving...

[lph]

Easy check: stand still, apply the front brake, and see if you can get that squeal just by moving the fork. If you can, it's not the brake.

Immobilizing the fork and moving just the wheel is a bit harder though. But if it happens every time you brake it probably is the brake.

[Catrin]

I called my LBS, they think it is just the brakes. I will try LPH's test when I get home today.

Edited: I did try her test, and the LBS is right. It is just the brakes, it doesn't happen when I am holding the front brake. Guess there is a lot more to discs than I knew :o

I do need to schedule some time at the LBS at some point and learn how to take care of them properly...

[Catrin]

Took the mountain goat to the LBS today to have them check my brakes. They were quite busy, but went to the trouble of explaining the process of how disc breaks break in and what has to happen. They also said that I have a light touch on the brakes which makes it much more likely to have noise :o The wrench couldn't really duplicate what I've noticed. It was very helpful and, most importantly, I know there is nothing wrong with my bike & I am not hurting it. If the noise continues after the breaking in process is complete then we will likely replace the semi-metallic pads with organic, but time will tell. They think they can actually do that under warranty if it is called for.

I love my LBS, they never talk down to me and I always leave understanding more than when I walked in the door.

[lph]

Cool! I find disk brakes a bit confusing. They're supposed to be less maintenance once you have them dialed in, but I find them finicky to adjust and especially to troubleshoot. The nice thing about v-brakes is I can take them off the bike, take them completely apart, find the problem and put it all back together again quite easily.

[Catrin]

Cool! I find disk brakes a bit confusing. They're supposed to be less maintenance once you have them dialed in, but I find them finicky to adjust and especially to troubleshoot. The nice thing about v-brakes is I can take them off the bike, take them completely apart, find the problem and put it all back together again quite easily.

It is always a little embarrassing when the mechanic can't reproduce something, but the wrench is much taller and heavier than I am. I would say he weighs at least 100 pounds more than I do and probably a little more than that. He is also over 6 ft, so seeing him on my little Jamis was quite funny :) One of the other wrenches said he looks like that on most bikes. He did say that a light touch on the brakes, especially at this stage, tends to set harmonics in motion.

They really do give a lot of free advice there and try other solutions before those that involve money. I think it is almost time to make cookies for them again :cool: