Historical Note: Bicycles Roll Along from Wooden Wagon Wheel to Alloy Tubing

Abstract

The evolution of the bicycle provides a good history of structural materials since the 1850s. The first machine that resembled a bicycle was made of a wooden beam with a wooden wagon wheel at each end. This presumably inspired the Hobby Horse, which had a forged iron beam for a frame, along with wooden wheels. The next step was the “boneshaker,” still with wooden wheels, but with the innovation of pedals, which allowed riders to keep their feet off the ground. Major reductions in weight came with the introduction of steel tubing for the frame and tensioned wire-spoke wheels, as in the high-wheelers of the 1880s. These breakthroughs came on the heels of the development of tube drawing and wire drawing in the new steel industry. With the introduction of the Humber “safety bicycle” in 1890, the evolution of the present-day diamond-frame configuration of the bicycle was completed. By this time, hardened steel components were available for the chain, cogs, bearings, and the chain wheel. In the previous year, John Dunlop had patented the pneumatic tire, and this invention took over the market for bicycle tires by 1895. The cotton-fiber-strengthened rubber-matrix tire was probably one of the earliest fabricated composite materials.The use of brazing to join the cold-drawn steel tubes led to the development of the diamond frame. Lugs held the ends of the tubes in place. The brazing alloys were, and still are, based on Cu-40%Zn and on the Ag-Cu eutectic alloy. Wood and bamboo were tried as substitutes for steel tubes in diamond frames during the past century, but the lack of an available method for joining the pieces together defeated these attempts to save weight. The main materials developments in bicycles over the next 80 or 90 years after the Humber safety were the introduction of low-alloy steels for tubing, primarily the Cr-Mo-0.3%C 4130-type steel, the substitution of aluminum-alloy extrusions for steel tubing for wheel rims after the 1950s, and the use of stainless-steel spokes instead of carbon steel.