The aim of the work reported here was to investigate the potential benefits of rear suspension systems for mountain bikes and to develop numerical models that could be used in future to help with the design of improved suspension configurations. As the basis for a study of the effect of rear suspensions, two bicycles were chosen: one with full suspension and one with only front suspension (hard tall). Apart from the rear suspension, all other aspects of the bicycles were closely matched. In order to control the number of variables, a special rolling road test rig was used. Eight subjects were asked to ride each bicycle on the rig in random order. Measurements were taken of pedal torque and speed, rear wheel speed, forward thrust at front axle and vertical acceleration at the saddle and handlebars. Physiological measurements were also taken, but these are reported elsewhere. A DADS model of the rolling road rig, bicycle and rider was created and numerical simulations were performed. The results of the numerical simulations compared well with the experimental results. Unmeasured parameters predicted by the DADS model could therefore be used with reasonable confidence to aid the understanding of the suspension performance. Physiological results, mechanical measurements and simulation results all indicate that the full suspension bicycle shows a significant improvement in terms of comfort and energy expenditure when riding over regular bumps. The good correlation between measurement and simulation provides a tool that can be used in future for optimization of bicycle suspension design.