Simplified schematic of hub. Roller chain transfers torque to the sproket. During forward pedaling, the roller-pin clutch on the left catches and rotates with the sproket. Torque is also transfered through the gears (not shown) in the gear box to the "anti-sprocket," which moves in the opposite direction of the sprocket. During backward pedaling, the clutch on the right catches and rotates with the anti-sprocket. Regardless of pedaling direction, one clutch catches while the other is free to rotate. By connecting the clutches to the spokes of the wheel, we have a wheel that moves forward regardless of pedaling direction.