Adjustable height seat post

An adjustable height seat post, comprising

• supporting means connectable to the bicycle frame,
• a quill associated with said supporting means and having a head suitable to clamp the rails of the saddle of a bicycle, or the like, in the desired position,
• hydraulic adjusting means, associated with said supporting means, for lifting or lowering said quill in the desired position selected by the user,
• said hydraulic adjusting means comprising a cylindrical chamber inside which a piston assembly is foreseen, and
• valve means, suitable to selectively open or close an hydraulic path through said piston assembly for selectively lock or unlock the position of said piston assembly relative to said cylindrical chamber,
• said valve means comprising at least a valve body, associated with said piston assembly, which is selectively rotatable from an open position, in which the hydraulic path through said piston assembly is open, to a closed position in which the hydraulic path through said piston assembly is closed,
• said hydraulic adjusting means comprising a valve cartridge assembly comprising a piston shaft connected to said piston assembly which, in use, is installed facing downwards and rigidly connected to said supporting means,
• said seat post further comprising valve actuation means associated with said supporting means and suitable to selectively rotate said valve body between said open position and said closed position,
• wherein said valve actuation means comprise an actuation rod passing through an axial cavity of said piston shaft, and suitable to selectively rotate said valve body between said open position and said closed position.