The featherbed frame is a motorcycle frame design that was a precursor to most modern motorcycle frames. The featherbed frame was initially designed for racing use. It features two loops of steel tubing encircling the engine and a swing arm that uses hydraulic shock absorbers to soften the ride.
Britain's Norton Motorcycles Ltd. was responsible for the development of the featherbed frame. Other companies, such as Triumph motorcycles and Birmingham Small Arms (BSA), also fitted their engines into the featherbed frame. Norton Motorcycles, however, eventually patented the design and became the sole owner of the original featherbed frame design.
Prior to the release of the featherbed frame, most motorcycle designs used the hardtail frame as the platform for their motorcycles. Coupled with a spring seat, the hardtail frame made for a very rough ride and was also difficult to handle at racing speeds. Tire design of the early to mid-1940s coupled with the rigid frame created motorcycles that would literally bounce off of the track after hitting a significant bump. The newly designed featherbed frame got its name from a racer who described the ride as if he were floating on a featherbed.
The prototype frame design used shock absorbers from an automobile to soften the motorcycle's harsh riding traits. Eventually, purpose-built shock absorbers would replace the automobile units on the featherbed frame. The new frame design first made its racing debut in a road race where it convincingly topped all competitors. The riders described the motorcycle as being very easy to maneuver in traffic as well as feeling very solid and stable under them during the race. The new frame worked so well that many companies opted to place their engines in the Norton frame in order to have a competitive edge on the motorcycle racing circuit.
The frame is offered in two distinct sizes for the 350cc and 500cc Norton motorcycle engines. The size of the tubing is smaller on the smaller-engine equipped 350cc frame. With the size of the tubing being extremely important in the handling traits of the motorcycle, it was very dangerous to install the larger 500cc engine in the lighter 350cc featherbed frame. Hybrid motorcycles using other makes and manufacturers of engines were careful to closely match the size of their engine with the size of the Norton frame. The success of the frame design was such that it continues to be reproduced by several companies around the world today.