C-21 exercise bike comes fully equipped to help build cardio endurance and target lower body muscles without causing impact strain on sensitive joints. 9 kg / 20 lb flywheel creates a smooth cycling motion for consistent cadence.Self-generating motor – no power adapter, no wires, no sockets, just you and the bike. Integrated speakers with Bluetooth connectivity - workout to your favourite tracks and movies. Signature adidas Ultra Series red LED lighting powers up when you create energy. Workout with your chosen fitness app to explore classes and challenges via your phone, tablet or TV