Abstract

The forward triangle of a bicycle frame incorporates steel lug pieces which are made out of ordinary tube sections, without collars. The end of the lug tube is readily and inexpensively shaped by a simple mitering operation to fit at any particular location and at any particular angle for any particular frame size or frame geometry. The shaped end of the lug tube is pulse tungsten inert gas (TIG) welded to the related frame structure. The weld area can be heat treated, prior to the brazing of a frame tube, so that only the relatively short tube lengths of the lug tube and associated frame structure need to be subjected to the heat treatment temperatures. An all steel frame is constructed by brazing a steel alloy frame tubes into each related lug tube and onto the associated frame structure. This forms a connection which utilizes the strength of the TIG weld and brazing, the elasticity of the brazing, and the damping of shock frequencies resulting from the combination of the steel and brass materials. Carbon fiber frames are constructed by gluing carbon fiber frame tubes to the TIG welded steel alloy lug tubes and associated inner, TIG welded, support tubes. The physical qualities of the steel alloy parts are closely matched to the physical qualities of the carbon fiber frame tubes to provide a strong, lightweight, front triangle, bicycle frame which is not subject to catastrophic failure of metal parts.