A swingarm bush is a component used in a motorcycle's rear suspension system to provide a pivot point for the swingarm. Typically made from materials like rubber, polyurethane, or metal, the bush is installed in the swingarm’s mounting points or brackets. It helps reduce friction and vibration while allowing the swingarm to move smoothly and absorb shocks from the road. Proper functioning of the swingarm bush is essential for maintaining the stability and handling of the motorcycle, as well as prolonging the lifespan of the suspension components.