Intermittent disc brake rubbing My partner has a Kona Sutra with Avid BB-7 disc brakes. The front brake rubs intermittently on the rotor. I just went to see if I could figure out what the problem was and right now the disc runs true and quiet. The disc is a Shimano CenterLock on an Alfine dynamo hub.

Usually when we notice the rubbing it is part way through a ride. Our usual route takes us down a relatively steep hill early in the ride. I'm wondering if the rotor could be warping from the heat of braking down the hill – though I'm not sure why it would stay warped for the next 20-30 minutes (for the rest of the ride).

Any suggestions for things to check or ways to isolate the problem?
After working on this for way to long, I think the problem is a combination of oversized dropouts and not enough tension on the quick-release. I discovered that if we stopped and loosened the quick-release while making sure that both axle ends were seated in the dropout that noise would stop.

I think what was happening is that the force applied on the disc would cause the wheel to shift a bit in the dropout and start rubbing. Each time I did this I tightened the quick-release a bit and after a few tries it seems to be resolved. I'm surprised by how much I had to tighten the quick-release. It is way tighter on this bike than on my bike which has rim brakes.