Steven Doetschman explains pedal types and threading used on Schwinn Airdyne exercise bikes. The most important thing to know is that the left pedal uses reverse (left-hand) thread — it tightens counterclockwise and loosens clockwise, the opposite of a standard bolt. Many pedals are stamped with an “L” or “R” to indicate which side they belong on. Using the wrong threading direction or installing a pedal on the wrong side can strip the crank arm threads and cause costly damage.