When I pull on the rear brake lever it builds up, then with a "click" it releases. After this threshold point the brake works perfectly. Is this the same problem someone had with an air bubble behind the bladder? It seems that one piston moves more easily than the other. This only happens after the pads are worn down to a certain point and the pistons have to move out further to make contact. I pulled the pads out and pushed the pistons all the way in, then I reset everything back up and it worked fine for 1 ride.