Disc singing to me
 

Just got the bike back from the LBS, rides like a champ. Shifting is smooth, brakes (BB5) feel solid, but the rear is singing to me the whole ride. Things look fine, but I am real new at this ( too obvious? ) I have done a few searches but have not seen a solution. Will most likely bring it back to the LBS on Tue, but if it is most likely something minor I would like to see if I can do it. Driving me nuts.

From a safety standpoint, it's nothing to worry about. Mine do too (at times). I think a slight warping of the rotor causes it to rub against the pads and the rubbing causes mine to "ting". Sometime, I'll pull the levers and release real quick (snapping action), it'll go away. If you want to try a few cheap easy things, make sure the rotor screws are tight (and evenly torqued), and clean the rotor with rubbing alcohol. If you have adjustable pads, perhaps dial them out a tad.

I will try those suggestions. thanks

My guess is a bent rotor or the caliper is not alligned properly.

The reason that MudPie suggested this is because if rotors get oily or contaminated they can howl when you apply the brakes. Cleaning with alcohol helps but if your pad are also contaminated the howling will continue. Incidently they will still work when contaminated so if you can live with the noise great

If it is singing when the brakes are not engaged, then that means you are getting contact between pads and rotor when you should not.

Try a couple of things:

-clean and lube the setup. A little friction can make the return spring hang up a bit and the pads end up dragging lightly on the rotors.
-add a little more spring tension to the system. I know my BB7's have a spring adjustment screw on them. If so, then just give it a turn. If not, then maybe you could pop the pads and spring out and flex the spring out a bit to give it more tension.

jim

Is it on key?

:rolleyes:

It may be a simple alignment issue. I used to experience squealing brakes until I learned to re-align the calipers to the rotors. I now make this adjustment regularly. It is not hard to do.

The directions can be found here.....

Avid BB5 User Manual

In brief, the steps are......

ALIGN THE CALI PER
A. Use your fingers or a Torx® wrench to turn the inboard pad adjustment knob
clockwise until the rotor is centered in the caliper. This positions the pads for
the next step in the installation.
B. Make sure the CPS bolts are loose enough for the caliper to move freely.
C. Squeeze the brake lever to compress the brake pads firmly on the rotor.
D. While still holding the brake lever, tighten the CPS bolts. Once they are tight you can
let go of the lever.
ADJUST THE PADS
Back the adjustment knob off (counterclockwise) until the rotor spins freely.
Now you can dial the pad in or out until you find the brake action you prefer
(make sure, of course, that there’s no drag on the rotor). If you can’t seem to
get the feel you like, or the rotor is dragging, repeat step 5.

Try backing off one or both barrel adjusters and/or tightening the caliper mounting bolts.

Interestingly, I have BB7s and rubbing alcohol made them squeal like banshees. Windex on the other hand quieted them down instantly. With alcohol, I could even make them howl just by running a paper towel around the rotor.