A bicycle handlebar assembly having a handlebar attachment mounted fixedly connected to a fork of the bicycle and oriented forwards with respect to it, elongated mainly according to its own longitudinal axis (B) inclined with respect to the direction of forward movement (A) of the bicycle by an angle a smaller than +/12; a handlebar rod, provided with handgrips at opposite ends thereof; a front seat) formed in the handlebar attachment for abutment of a central area of the handlebar rod; a stop removably fixed to said handlebar attachment through attachment screws to lock the handlebar rod in the seat of the handlebar attachment. The stop comprises at least one open strap, with a central portion arranged in circumferential direction around the handlebar rod and two rear arms extending in tangential direction with respect to the central portion for fixing to the handlebar attachment by means of the attachment screws. The rear attachment arms of the strap extending in the tangential direction thus face backwards with respect to the direction of forward movement (A) of the bicycle and thus allow the front section of the handlebar assembly to be reduced.

A three-piece stem of a bicycle includes a stem body, a bottom pipe, and a middle element. A first torus portion and a second torus portion are disposed at two ends of the stem body, respectively. The bottom pipe is disposed in the second torus portion of the stem body. The middle element is disposed between the second torus portion of the stem body and the bottom pipe. A connecting element couples the second torus portion of the stem body, the bottom pipe, and the middle element together, such that the second torus portion of the stem body, the bottom pipe, and the middle element are fixed tightly to a front forked upright pipe collectively, thereby enhancing the ease of assembly and the binding strength upon completion of assembly.

Handlebars having a master tube, two handgrips at opposite ends of the master tube, a stem for attaching to a fork, and at least one portion with doubled section, the cross section of which comprises an upper outer wall, a lower outer wall, an upper inner wall and a lower inner wall. The upper outer wall is distanced from and joined to the upper inner wall, the lower outer wall is distanced from and joined to the lower inner wall, and the upper inner wall is distanced from the lower inner wall.