Rear suspension for a bicycle which includes a rear swing arm which carries the hub of the rear wheel and pivots via at least two pivot points on a frame carrying a bottom bracket. Subsequently, a limiting part calculates an estimated slip ratio \u03bb and an estimated driving torque Td on the basis of the movement speed v, the rotational speed \u03c9 and the actual torque value Tm. The head structure is configured to be placed within the rectal cavity of a patient such that either a contact surface on the head structure or the fluid itself directly contacts a portion of the rectal mucosal membrane.