![avid bb5 mechanical disc avid bb5 mechanical disc](https://www.xxcycle.com/marques/avid/images/large/54634.jpg)
![avid bb5 mechanical disc avid bb5 mechanical disc](https://i.ytimg.com/vi/Dkp2WFjuqYg/hqdefault.jpg)
The Avid BB5 brake pads can be difficult to get completely parallel to each other and to the rotor, due to (1) the shape of the pad and spring that holds them apart, and (2) the caliper angle is adjustable in 2 separate axes of rotation and 2 axes of translation (most brakes don't have those extra conical washers). I have a lot to say about the BB5's, so sorry for the long response. Could it be a slight manufacturing defect on the front one that causes the inboard pad to sit at a slight angle (it's not totally clear with the naked eye). I took it to my LBS, he seems to think it's an acceptable set up and just needs riding, but did not say why the rear seems to be acting differently to the front, despite setting them up in the same way multiple times. Nothing seems to make any difference either with trying to bring the position of the inboard pad lower as it makes contact, or the squealing itself. And it's new so nothing is contaminated and I've used alcohol on everything just to be sure. I've tried the sanding the rotor and pads trick. I have played around with different pad adjustments as well as caliper alignment. I say this because the while a similar thing is happening on the rear rotor, it is not quite as pronounced (ie, the inboard pad side seems to be hitting a smidge more square on, and does not squeal). The marks end further inward toward the centre of the disk on the outboard pad side, than on the side where the inboard pad hits it.īecause of the way the brake works (bending the rotor at an angle as it is pushed into the stationary inboard pad), this would make sense to me as the very top of the rotor hits the inboard pad, and because of the angle, leaves a gap lower down. Notice the marks where the pad material has transferred onto the rotor in each picture. The following image is of the drive side of the front disc rotor (where the rotor is pressed into the inboard pad.) The following image is of the non-drive side of the front disc rotor. As I tried to bed in the brakes, the front one squeals quite heavily, the back does not.