A unitary monocoque frame is provided for a bicycle including a right half shell having a peripheral edge and a left half shell having a peripheral edge symmetrical with the peripheral edge of the right half shell. The right half shell includes an integrally formed head tube portion and an integrally formed seat tube collar. The left half shell includes a curved surface to join with the head tube portion and a cupped recess to receive the seat tube collar. A tongue extends along at least a portion of the peripheral edge of one of the right and left half shells. A groove extends along at least a corresponding portion of the peripheral edge of the other one of the right and left half shells. The tongue and groove are in mating engagement to join the right and left half shells forming the unitary monocoque frame.