Abstract
This paper deals with the effect of steering system design and tyre properties on the behaviour of a motorcycle. First the kinematic analysis of the system is carried out using a 3D model, the displacement of the front tyre contact point (caused by the roll and steering angles) is analysed and its influence on the steering torque is discussed. Then the steady turning behaviour is studied by means of a dynamic model, which is based on Newton-Euler equations and takes into account suspension deflections. Results are presented in terms of steering torque, which is an index of vehicle handling, and a steering ratio, which shows the understeering or oversteering behaviour of the vehicle and is related to safety.