Disc Brake Question regarding flex and noise.
I have a hardtail with Avid BB7 mechanicals. Just a quick question... If I hold down the rear brake as I'm sitting on the bike and kind of move the bike front to back, despite the rear brake being locked, I hear a flex sound, I guess you could say. It's a pop sound that echos throughout the frame, but I think it originates in with the rotor/pads, perhaps they're getting just enough force to move a hair and that's how it makes a sound, I don't know. Trick is, the front doesn't do this at all. Just wasn't sure if anybody else had noticed the same thing or not. Basic question, but one I'm looking for an answer for at that. Thanks!
What you could be hearing is the "play" of the pads within the caliper body. Once you've got your brakes fully engaged, the pads become part of the rotor and when you rock the rotor back and forth, the pads will follow the rotor and knock against the cavity it is housed in. The front possibly doesn't do it as bad because the front suspension cushions the back and forth motion somewhat. You'd probably hear the same thing going on with a rigid fork. I wouldn't worry about it though, as actual braking situations don't subject the pads to the extreme back and forth rocking motion you're making.
Originally Posted by dminor