Summary
The post discusses the significance of the motorcycle frame, highlighting various types and focusing on the featherbed frame. Invented by Rex McCandless in 1949 for the Norton Motorcycle Company, the featherbed frame addressed the limitations of previous designs under racing stress. The post references the relevant patent and explains the technical advantages, particularly in terms of stiffness and maneuverability. It further notes the adoption of this frame by other manufacturers and its lasting influence on motorcycle design.
First published 16 October 2014.
The chassis or frame of a vehicle is a component of fundamental importance. It acts as a skeleton that defines the shape of the vehicle and holds all associated components together. Motorcycle frames take several forms, including single cradle, half-duplex cradle, full-duplex cradle, perimeter, beam, and trellis designs. Although the single cradle or single down-tube cradle frame is the most commonly encountered type, it is generally considered inferior to its more complex counterparts in terms of handling and performance.
Origins of the Featherbed Frame
The Featherbed Frame is a type of full-duplex cradle, or double down-tube frame. It was invented by Mr Richard McCandless (known as Rex) in 1949 for the United Kingdom based Norton Motorcycle Company. Rex developed the Featherbed Frame primarily to improve the performance of Norton’s racing motorcycles for the Isle of Man TT, where several of Norton’s earlier Garden Gate frames had buckled under the extreme stress of racing.
The term “Featherbed Frame” was coined by Mr Harold Daniell, an elite Isle of Man TT racer who had won several trophies during his career. After riding the new frame developed by Rex, he declared that it was like
“riding on a featherbed”
when compared with riding the “garden gate” frame.
The Patent
Patent GB664667A, entitled A new or improved frame for a motorcycle, discloses the features of the Featherbed Frame. The patent claims a frame for a motorcycle comprising two parallel rectangular loops, each formed from a single length of tubing, the ends of the tube forming each loop crossing and being welded to each other at the top front corner of the loop, with the free ends of the tube extending beyond the crossing point welded to an inclined head tube adjacent to its top and bottom respectively.
Performance and Legacy
The Featherbed Frame is extremely stiff and provides excellent resistance to the stresses arising from road conditions, direct load, and engine torque. It delivers excellent manoeuvrability, particularly during cornering at high speeds.
The frame became the standard for Norton’s production motorcycles and was widely adopted by other motorcycle manufacturers. Several hybrid custom motorcycles, including the TriTon, NorBsa, and NorVin, were built using Norton’s frame. Royal Enfield subsequently adopted this frame for its Continental GT model.
Disclaimer: This article is for general information and does not constitute legal advice. Readers should consult a qualified attorney before acting on any matter discussed here.