A couple days ago the old bike developed an audible and periodic creak. I've narrowed it down to the crank/BB area. The parts are fairly dated - a few years old I'd say. Suntour crank with riveted rings and a brandless BB. The creak makes itself known at the top of every pedal stroke on the drive side. I can feel it in the pedals and its loud enough to hear. I cleaned off and lubed the moving parts without taking it apart but the creak persists. Anyone have an opinion?