Motorcycle roadracing term for the angle between the center plane of the motorcycle and the vertical plane. The more the motorcycle is leaned over, the greater the lean angle. High lean angles are necessary when cornering a motorcycle at high velocity, but too great a lean angle results in loss of traction and often a crash. Riders employ a technique called hanging off in order to alter the rider-motorcycle system's center of mass and thereby minimize the lean angle necessary to negotiate a corner at a given velocity.
Establishing and maintaining the correct amount of lean angle is a balancing act that a motorcycle roadracer must master in order to ride fast.