What is meant by “suspended” (sprung) and “non-suspended” (unsprung) weights?
The dynamic behaviour of a motorcycle depends on the extent and arrangement of its weights. These will be “suspended” (sprung) weights, if they are not in contact with the ground, or if they are separated from the ground by suspensions (rider, engine, tank …); conversely, they will be “non-suspended” (unsprung) weights if directly in contact with the road (wheels, tyres, brakes, part of the suspensions, wheel spindles…). These two types of weight have different effects on the dynamic behaviour of the bike. Basically, the difference, in terms of the longitudinal plane in which the bike is contained, is that the former weights should move as little as possible, while the latter should be free to move very easily (to follow any bumps in the road): for this reason, an effort is made to minimise unsprung weight by using very light materials. The actual speed range of sprung weights is between 0.1 and 0.2 m/s, while unsprung weight speed is around 1 m/s.
