Steady turning of motorcycles

When driving along a circular path, the rider controls a motorcycle mainly by the steering torque. If the steering torque is low and the vehicle is moderately over-steering, a good handling feeling is perceived by the rider. In this paper, non-linear steady turning results are analysed over a wide range of forward speeds and lateral accelerations, and different 'driving zones' are identified by considering the steering torque transition speeds and steering angle critical speed. A parametric linear model of steady turning, concerning both the steering torque and the steering angle, is developed and simple parametric expressions of transition speeds and the critical speed are obtained. Steady turning tests involving different motorcycles are presented, the transition speeds and critical speed are found by linear fitting, and the characteristics of the different driving zones are investigated. The primary purpose is to determine the conditions at which the operational safety and handling of the vehicle do not impose severe demands on rider skill for control and adequate path-following properties, i.e. to identify a 'preferable driving zone'.