Bicycle steering and roll responses

Abstract

This article investigates the effects of different steering geometries on the steering response, system stability and frequency response of bicycles. A computer model was developed using Simulink™. The model simulates different bicycle designs allowing several different steering geometries to be quantified in terms of performance. It was validated by data available in literature and from an experimental investigation conducted with a bicycle fitted with steering and roll sensors. Three key variables were examined in detail: the head tube angle, front fork rake and bicycle speed. Their actual importance was determined by systematically changing each key variable one at a time while keeping all other terms constant. Large variations in roll and yaw responses show how sensitive bicycles are to small changes in head tube angles and rake dimensions. At higher speeds, the observed steering responses support the common observation that bicycles are more stable and easier to ride at higher speeds. These simulations show the importance of correctly designing a bicycle’s steering geometry in order to optimise steering performance and the sensitivity of bicycles to small changes in geometry.