Motorcycles have a steel or aluminum tube or box frame. Some have full frames that encompass the engine, while others have partial frames to which the engine is attached. Motorcycles with partial frames tend to be lighter in weight than those with full frames.
The frame also supports the suspension system, a collection of springs and shock absorbers that helps to keep the wheels in contact with the road and cushions the rider from bumps and jolts. The front wheel and axle are mounted on a telescoping fork with internal shock absorbers and internal or external springs. The suspension on the rear wheel and axle consists of either a pair of shock absorbers or a single shock located within the frame.