The bar has on its outer tube a sleeve+shaped body made of thermoplastic material and provided with an external thread. The body has an extension provided with longitudinally extending slots and an external taper. A sleeve-shaped threaded nut is guided on the external thread of the body and has an internal taper which cooperates with the external taper of the extension. For improving the clamping of the inner tube of the handle bar in the sleeve-shaped body, the angle of inclination of the internal taper of the sleeve-shaped threaded nut is smaller than the angle of inclination of the external taper of the extension of the body provided with an external thread.
