For aerial maneuvers, "frontside" and "backside" identify the direction of rotation of a spin. For instance a regular rider doing a frontside spin off a jump would rotate their body counterclockwise opening their shoulders up so that their "front side" is the first side of their body going forward off the jump in the first 90 degrees of their spin. A regular rider doing a backside spin off a jump would rotate their body clockwise closing their shoulders so that their "back side" is the first side of their body going forward off the jump in the first 90 degrees of their spin.