Abstract: A torque transmitting, bicycle frame coupling which connects to the frame tubes, replacing a portion of those tubes and having teeth on their engaging faces. Proper installation of two such couplings allows up to a 25 inch men's style bicycle with up to 700C (26 inch rim diameter) wheels to be cut in two pieces so that it fits in a suitcase with a combined height, width and girth measurement no larger than 62 linear inches and then be put back together with no loss of original frame geometry or stiffness. Each coupling is actuated, pulling the bicycle pieces together and joining them through use of specialized teeth under compression by a threaded lug, a removable-shoulder lug with a removable shoulder and a threaded coupling nut. The removable shoulder makes the nut and shoulder replaceable, and makes possible an additional shoulder on the tube connecting end of the removable-shoulder lug to keep the nut from slipping onto the frame and scratching the paint.