A device for mounting a wheel of a bicycle on a frame, including: an inner hub rotatably mounted in a portion of the frame, an outer hub forming a central zone of the wheel, a quick-tightening mechanism that includes a male portion projecting from a first of the inner and outer hubs, a female portion provided in a second of the hubs, axial abutments for retaining the outer hub supported against the inner hub, and a mechanism for positioning the axial abutments, the positioning mechanism not being active upon completion of the tightening of the wheel. The quick-tightening mechanism is equipped with a lever that is pivoted by the operator to provide the necessary force for the axial tightening of the outer hub of the wheel against the inner hub. In a particular embodiment of the invention, the axial abutments include a plurality of balls, and the mechanism for positioning the axial abutments include ramps on which the balls roll.