A Dynamic System Model of an Off-Road Cyclist

Abstract

To optimize the performance of off-road bicycle suspension systems, a dynamic model of the bicycle/rider system would be useful. This paper takes a major step toward this goal by developing a dynamic system model of the cyclist. To develop the cyclist model, a series of four vibrational tests utilizing random inputs was conducted on seven experienced off-road cyclists. This allowed the transfer functions for the arms and legs to be determined. To reproduce the essential features (i.e., resonance peaks) of the experimental transfer functions, the system model included elements representing the visceral mass along with the arms and legs. Through simulations, the frequency responses of the system model of the rider in each of the four tests were computed. Optimal stiffness and damping parameter values for each subject were determined by minimizing the difference between the experimental and simulation results. Good agreement between experimental and simulation results indicates that modeling the rider as a lumped parameter system with linear springs and dampers is possible.