Motorcycle frame
All the major manufacturers (AJS, Ariel, BSA, Matchless, Norton, Sunbeam, Triumph, Velocette, BMW, DKW, Ducati, Moto-Guzzi, Harley-Davidson and Indian) used steel tubing.
[4] Following the technology being used by the Formula One industry, Armstrong designers Mike Eatough and Barry Hart created the first motorcycle using a carbon fiber frame to compete in Grand Prix racing.
One of the earliest examples was the 965cc motorcycle produced by Louis Janoir in 1920, which used pressed steel for the frame, rear swinging arm, and the front forks.
French industrialist and engineer Georges Roy attempted in the 1920s to improve on the bicycle-inspired motorcycle frames of the day, which lacked rigidity.
Its new type of monocoque body solved the problems he had addressed, and along with better rigidity it did double-duty, as frame and bodywork provided some protection from the elements.
Strictly considered, it was more of a semi-monocoque, as it used a box-section, pressed-steel frame with twin side rails riveted together via crossmembers, along with floor pans and rear and front bulkheads.
[12] A Piatti light scooter was produced in the 1950s using a monocoque hollow shell of sheet-steel pressings welded together, into which the engine and transmission were installed from underneath.
[15] The F750 event at the 1973 Isle of Man TT races was won by Peter Williams on the monocoque-framed John Player Special that he helped to design based on Norton Commando.
[18] The bike had other innovative features, including an engine with oval shaped cylinders, and eventually succumbed to the problems associated with attempting to develop too many new technologies at once.
It was described by Cycle World in 2000 as a "monocoque backbone...a single large diameter beam" and "Fabricated from a combination of castings and sheet-metal stampings".
A trellis frame connects the steering head to the swingarm pivot as directly as possible using metal tube arranged in triangulated reinforcement.
Using lattice girder principles, a trellis frame is typically constructed of round or oval section metal tubular segments that are welded or brazed together.
A well-designed trellis frame should provide a strong, lightweight structure that simplifies placement of engine and components, and gives good access for maintenance.
For rider comfort, a motorcycle's engine can be mounted on rubber bushings to isolate vibration from the rest of the machine.
[24][25] The 1946 Vincent Series B Rapide was designed with an advanced chassis, termed a "tour de force for its day,"[26] that included a stressed member engine.
[27] BMW's R1100 series twins of 1994 relieved the frame of stress entirely, with the engine carrying the total load from the front Telelever fork to the rear Monolever.
