Investigation of the influences of tyre-road friction and engine power on motorcycle racing performance by means of the optimal manoeuvre method

This paper investigates the influences of the tyre-road friction and of the maximum engine power on the performance of a racing motorcycle. For this purpose the optimal manoeuvre method is applied, which essentially simulates an ideal driver and computes the minimum lap time for a given motorcycle and a given track. The absolute performance of a racing motorcycle is strictly related to the braking and acceleration capabilities. Braking is limited by front- or rear-tyre skidding and by a stoppie event, whereas acceleration is limited by rear-tyre skidding and by a wheelie event. Furthermore, the engine power constitutes a limiting factor during propulsive phases. Effectively the weights of these limiting factors change with the tyre-road friction condition and with the engine power availability. As a consequence, the manoeuvrability of a racing motorcycle varies and riders need to adjust their strategies properly in order to achieve the best performances allowed in any condition. For this purpose a simple L-curve manoeuvre is considered in this paper. First, a detailed description is reported, and then brake and acceleration limiting conditions are considered with respect to a reference configuration. Next, a parametric analysis is carried out at variable friction and maximum engine power, and their influences on lap time are examined. Finally, two representative configurations are evidenced, i.e. lower friction and lower power; furthermore, brake and acceleration limiting conditions are derived analytically by means of a simplified motorcycle model. Accordingly, the representative manoeuvres are interpreted, and the influences of the friction and engine power on curve entering and curve exiting using optimal strategies is examined.