Infinitely adjustable:- Determine your individual pedaling radius -Due to the infinitely adjustable length of the pedal crank arm, you can optimize the pedaling radius to your individual range of motion and use of force. The crank radius can be reduced from the maximum position to almost the 0 position via the slot nut. Easy installation:- Training with limited knee or hip mobility -The bicycle crank adapter allows people with limited knee and/or hip mobility to train effectively and gently on the bike or ergometer. Athletes (e.g. after a break due to injury) can also return to cycling safely and in a controlled manner. Suitable for ergometers:- Universal retrofit kit for all common bicycles/ergometers -The WX Vario is designed for all common bicycle cranks. It is mounted directly on the existing crank or crank arm. Using the spacers supplied, the invalid crank adapter can be mounted even with unusual cranks.