From the main page: > The precision machined flywheel silently spins at 14 times your pedal speed. The high inertia of the flywheel helps keep the pedals movin

From the main page: > The precision machined flywheel silently spins at 14 times your pedal speed. The high inertia of the flywheel helps keep the pedals moving at a smooth pace, sort of like a mini spin bike.