The Dual Laser Knee Track does just that, tracks the knee location through the pedal stroke. It bolts directly on to the front of the Purely Custom Size Cycle and is equipped with a two Stanley Fat Max® self-leveling lasers. It also comes with a measuring scale that you can choose to affix to the unit to measure the distance from the center of the bike to the knee to make sure both knees are equidistant from the center.