In most bicycles, the only suspension systems for minimizing the impact of uneven roads on the rider and the bicycle is a combination of the air in the inflated tires and the flexure of the cyclist’s knees. Some utility bicycles and older bicycles also have springs under the saddle.
The advent of mountain bicycling (and, to a lesser extent, BMX riding) as a serious sport led to the invention and improvement of hydraulic shock absorbers on the front fork. These shock absorbers minimize the severe beating on the comparatively delicate threads and bearings in the bicycle’s headset during cross-country rock-hopping and stump-jumping. Suspension mechanisms have also been developed for the rear triangle of these bicycles to provide for increased shock absorption and better control while riding on rough terrain.