Shock absorber with bidirectional selective block, wheel group and motorcycle thereof

A shock absorber comprising:

• a main sheath and a main piston sliding inside the main sheath in a sliding direction, the main piston comprising a main rod coming out of the main sheath and a main head contained inside the main sheath, the main sheath being filled with hydraulic fluid,
• the main rod and the main sheath being suitable to be mechanically connected respectively to a wheel and to a frame or vice versa,
• a secondary sheath fluidically connected to the main sheath and provided with at least one damping valve comprising holes suitable to allow a calibrated passage of the hydraulic fluid of the main sheath,
• wherein the secondary sheath is connected to the main sheath by a first and a second passage placed at opposite ends to the main head of the main piston, in a sliding direction, the first passage allowing the flow of fluid when the main head approaches the first passage in a compression motion and the second passage allowing the flow of fluid when the main head approaches the second passage in an extension motion,
• wherein the secondary sheath comprises a control valve movable, according to a regulation stroke, between an unlocking position, in which it does not interfere with said first and second passages, and a blocking position, wherein it occludes said first and second passages, and
• wherein, when the control valve is in the blocking position, the main piston is locked in position within the main sheath and is unable to move in the sliding direction.