The seat post for bicycles and other vehicles in general includes at least one support element associated with a frame of a bicycle, which can be placed along a substantially vertical direction of installation and able to support a saddle for bicycles having at least one fastening element, at least one positioning assembly placed at the top extremity of the support element and having at least a locking device able to retain the fastening element, and the locking device having at least one damping layer able to dampen vibrations transmitted from the ground and other unevenness.