Study of the effects of low-velocity impact on a composite bicycle down tube

This study evaluates, by experiment and numerical analysis, the effects of a pebble thrown from the front wheel and hitting the down tube of a carbon-epoxy bicycle frame (the Guru Cycles Photon R). The performance of the down tube is based on the retention of its mechanical properties when performing a load test before and after an impact event. The results show that the down tube experiences a 4-5% loss of rigidity after an impact of 1.5-6 J. A parametric analysis of the effects of fibre orientation established a down tube stacking sequence that would increase its rigidity by 5.6%. With this new configuration, the effects of an impact on the tube was reduced and its residual rigidity after 1.5-6 J impacts increased by 1.5-2%.