Built to deliver the optimum indoor cycling experience, the C-21x features a solid 16 kg flywheel and 8 levels of resistance the C-21 is ideal for steady-state and interval training. Complete your ride anywhere with the self-generating motor eliminating the need for a power outlet and transport wheels to conveniently store your bike in between uses. The signature adidas Ultra Series red LED lighting powers up when you create energy, encouraging riders to maintain momentum and test their limits.