A suspension system for a wheeled vehicle (20) is provided, said suspension system being adapted to support at least one wheel (1) of said vehicle (20) and comprising at least one shock absorbing device (2) adapted to be activated as a result of the motion of said at least one wheel (1) in a direction substantially vertical, said suspension system further comprising electrical power generating means in fluid connection with said at least one shock absorbing device (2) so that the activation of said at least one shock absorbing device (2) results in electrical power being generated. Furthermore, said suspension system comprises means for absorbing at least partially the electrical power generated, the absorption of electrical power resulting in the stiffness of said at least one shock absorbing device (2) being varied as a function of the electrical power absorbed.