Motorcycle roadracing term used to describe a crash in which the bike is leaned over while cornering and flips back up towards the outside (i.e. the high side). A high side usually occurs when rear wheel traction is suddenly lost and the
rider's panic causes him to abruptyl close (chop) the throttle. As a result, the rear wheel suddenly and forcefully regains traction, violently flipping the bike away from the direction of lean and throwing the rider skyward. Most racing injuries occur as a result of a high side since the rider has much further to fall.
The flip side of this (no pun intended) is a
low side crash. These crashes are usually minor since the rider falls off much closer to the ground.