Most of the cycle ergometers developed suffer from the change in loading that follows a change in pedal rpm. The principles hitherto applied are mentioned. When a copper disk is running in the field of an electromagnet the braking force of the magnet has normaly the well-known proportional increase with the disk rpm. When the copper disk, however, is speeded up above a critical value, the braking force begins to decrease hyperbolically with the disk rpm. The use of this range of speeds where the product of the braking force and the disk rpm is constant has led to the construction by Lanooy of the ergometer described here. For the evaluation of the working capacity a progressively increasing load is of advantage. A device for a gradually increasing magnetizing current for the ergometer described is shown. Submitted on January 26, 1956