Abstract: A bicycle frame comprising a lug and a pipe to be fitted onto a projection at the lug, annular grooves opposite to each other being disposed at the mutual contact surfaces of the lug projection and pipe, wherein an unidirectional form memory alloy changeable of its outer diameter by heating is disposed in one of the opposite annular grooves, and the projection of the lug and the pipe are bonded at the fitting surfaces by means of a thermosetting adhesive, whereby the bicycle frame is high in safety and superior in productivity and has an improved bonding strength and mechanical juncture.