This drive unit is the ultimate in performance pedal-electric drive systems. In collaboration with designer extraordinaire Matt Shumaker, FFR has designed and hand built in the USA the ulitmate drive system for pedal-electric vehicles. It offers incredible power density, 93% efficiency, and runs quietly with its high-torque Gates HTD belt drive. The built-in adjustable slipper clutch minimizes driveline shock under hard bursts of acceleration. The drive is CNC cut from 6061 billet aluminum for maximum precision, minimal weight, and stunning looks. It's the drive we use at the heart of our 311 and 411R trikes, because it's the best.