Method of joining and reinforcing molded plastic bicycle frames

Abstract

A method of forming a tubular frame, e.g., a bicycle frame, from two substantially symmetrical frame-halves utilizes a plurality of interconnected half-tubular elements. Each half-tubular element has an exterior surface, an interior surface, and longitudinal edges that extend between the exterior and interior surfaces in the direction of the longitudinal axis of the half-tubular element. The surfaces of the longitudinal edges of the half-tubular elements are shaped such that corresponding edges of corresponding half-tubular elements in the left and right half-frames may easily be interengaged, and adjusted along the respective longitudinal axes of the half-tubular elements that are being joined. Preferably, the longitudinal free edges are stepped in the radial direction such that each level is substantially planar and smooth along the respective longitudinal axis of the half-tubular element. The longitudinal edge of one of the half-tubular elements may include parallel steps extending in opposite directions to thereby form a groove into which a step of the corresponding longitudinal edge of the corresponding half-tubular element in the other half-frame may be inserted. The latter joint type provides additional reinforcement of the connection of the half-frames. Further reinforcement in the stay area of the bicycle frame may be provided, either in the form of a reinforcement arch positioned within the tubular legs of the stays, or in the form of a one-piece, unitary inner stay element positioned between the outer stay elements that are part of the frame-halves.