A motorcycle frame is a motorcycle’s core structure. It supports the engine, provides the hinge points for both front and rear suspension, and supports the rider modern motorcycle technology by edward abdo pdf any pillion or luggage.
Also attached to the frame are the fuel tank and battery. At the front of the frame is found the head tube that holds the pivoting front fork, while at the rear there is a pivot point for the swingarm.
In the early days, motorcycles were little more than motorised bicycles, and consequently frames were tubular steel. While the use of steel tubing is still common, in modern times other materials such as titanium, aluminium, magnesium, and carbon-fibre, along with composites of these materials, are now used.
In Europe and the USA, steel tubing was the default material until recent times. Greeves 250DCX Sportsman, with cast alloy “downtube”, tubular steel rear subframe and semi-monocoque spine. The motorcycle engine is suspended from a single spine.
Spine could be a solid structure. The motorcycle engine is held in a single cradle with a single spine. The motorcycle engine is held in a double cradle with a single spine and single downtube. The motorcycle engine is held in place within a pair of separate cradles.