Probably the most likely place on your bike where threads can cross, clean out or restore damaged threads on crank arms with these Pedal Taps from Park Tool. These taps can be used with steel, alloy, or carbon crank arms with alloy threaded inserts. Made of high carbon steel, precision ground, and hardened to stay sharp. These taps fit all conventional tap handles. Set includes both right and left-hand threads. The 1/2" size is common on one-piece cranks and kid bikes, 9/16" are for adult bikes. Tap-3 kit includes a set of 2 taps, 1/2" x 20 TPI Tap-6 kit includes a set of 2 taps, 9/16" x 20 TPI