Worn-out disk brake pads, Avid BB7 Worn to the metal.
These pads came off the rear of my Pursuit after 1100 miles of use. On my last ride I was descending a hill while dragging the rear brake. I heard a "Clunk!" sound along with feeling something catching in the wheel or mechanism. In hindsight I think this was the end of the spring clip that got caught between the pad and rotor, and possibly the inner pad (right) shearing apart.
Notice that the installation tab of the outer pad scrapes the rotor when the pad wears thin.
