According to Master Spin Instructor Sabrina Fairchild: “The pedal stroke has two phases: the power phase and the recovery phase, which can be broken up into four quadrants. Quadrant one of the power phase is where the foot is parallel to the floor and the rider pushes the foot forward. Quadrant two of the power phase is where the rider pushes the heel downward. What may be misunderstood about the power phase is that it is not a constant vertical push because the foot is traveling in a circle. The power phase is traveling forward at the same time it is traveling downward, and the most powerful point of that is at 90 degrees.
Quadrant three of the recovery phase is where the foot is parallel to the floor again and the rider is drawing the heel straight back. Quadrant four of the recovery phase is when the heel lifts slightly. This fourth segment is the least understood as many instructors cue the hamstrings to draw the leg up, but it is actually done via the hip flexors, so the hamstrings are the antagonist. At the back of the pedal stroke the foot should feel “unweighted” while the opposite foot is doing the work in its power phase. A lot of people make the mistake of focusing on pulling up on the back side of the pedal stroke all the time, but the only time the recovery phase has any pulling up is during climbing and sprinting due to the amount of resistance on the flywheel.”