It’s like having two chainrings in one! With PowerTrac Elliptical rings, the larger-diameter section of the ring engages with the chain at the optimal point on the downstroke, or “Power Zone,” – between 1-5 and 7-11 on a clock face – to take advantage of your body’s natural biomechanical POWER: For example, during this section, a PTE 34t ring is equivalent to a 36t round ring. Similarly in the “Recovery Zone” (11-1 and 5-7), the smaller section on the PTE ring engages, maximizing EFFICIENCY in the weakest part of the pedal stroke; here the PTE 34t ring is equivalent to a 32t round ring.