An analytical approach to the structural design and optimization of motorbike forks

From a structural standpoint, motorbike forks must withstand the most diverse loading conditions that the normal use of the vehicle implies. By means of experimental analyses, the authors found the emergency braking to be the most severe loading case. This contribution presents a novel analytical model that, given a few geometric parameters of the motorbike and of the fork, allows calculation of the stress field on the legs under braking. The analytical model was designed to account for the unequal stress distribution on the two legs that arises from the geometrical asymmetry of single brake disc architectures. The model accuracy was tested by comparison with finite element analysis (FEA) and experimental stress analyses. Finally, the possibility of balancing the loads on the legs of single disc architectures was examined and some structural optimization strategies were proposed.