Hi all,

My wife recently bought a new bike, a Trek 29er mountain bike with mechanical disc brakes. Knowing nothing of disc brakes, I wondered how removing the wheel would come into play when changing a flat. Asked the guy at the LBS, who assured me there is really nothing to it. The wheels pop right off.

Today my wife had the inevitable flat. Rear tire. I fixed it. But after popping the wheel back on, it doesn't seem quite right; I think I hear some sort of rubbing. It is very faint, but it's there. I can't see what it is. The wheel itself seems properly seated. With no rim brakes there is nothing really obvious that would rub, or at least, not within my limited experience.

Could it be something in the brake mechanism? These things are hard to diagnose by description, but can anyone tell me whether there are some obvious things to look for?

Thanks in advance.