Lie flat on the floor with your lower back pressed to the ground. Interlace your fingers, and put your hands behind your head.
Bring your knees in toward your chest, and lift your shoulder blades off the ground. This is your starting position.
Straighten your right leg out and parallel to the ground while turning your upper body to the left, bringing your right elbow toward the left knee. Make sure your rib cage is moving and not just your elbows.
Return your arm and leg back to your starting position, and do the same motion on the other side to complete one rep (and to create the pedaling motion).