A one-piece crank arm for a bicycle is machined from high strength aerospace aluminum 7075-T6. One end of the crank arm has a threaded boss to be fastened in threads of an associated spider. The opposite end of the crank arm has a ball with a passage therein for connecting a pedal. The passage in the ball has a closed end and an axis which extends at a slight angle with respect to the axis of the threads of the boss. For weight reduction, elongated grooves are formed on opposite surfaces of the crank arm.
