A bicycle includes a frame with at the front end a head tube, a fork having at its upper end a steering tube extending upwardly through the head tube, and a stem attached to the handlebars. The stem has a clamp portion clamped around the steering tube. One or more spacer rings or bushings are arranged around the steering tube between the upper end of the head tube and the stem clamp portion. A mounting assembly for mounting a child seat on the bicycle is mounted around the steering tube. The mounting assembly includes a support body and a clamping element to attach the support body to the steering tube. The clamping element is coupled to the support body and is clamped around the steering tube and arranged between two of said spacer rings or between the head tube and a spacer ring.