The supporting tube (3) and tensioning bar (1) are joined by a connecting bridge (2). The tensioning bar (1) is inserted into the saddle tube of the bicycle and clamped by tightening wedges (20). The tensioning bar (1) consists of a tube (10) with tightening wedges (20) in several slots (11) and a circular groove (12) with a rubber ring (13). A tapered rod is turned axially inside the tensioning bar (1) by a spindle (40) and handwheel (41) to operate the wedges (20).
