Finite-element analysis (FEA) was performed for bicycle helmets making oblique impacts with a road surface, to evaluate the linear and rotational accelerations of the headform. Helmet rotation on the head was considered, modelling the helmet and retention strap interactions with the headform. The effects of frictional parameters on the response were explored, and parameters selected to reproduce experimental results. Predictions were made for two helmets, for a range of impact locations and tangential velocities. The design method for the peak headform linear acceleration was confirmed; it was hardly affected by the tangential component of the impact velocity. The peak headform rotational acceleration was investigated as a function of the helmet geometry, impact sites and velocities and the contributing mechanisms established. (C) 2007 Elsevier Ltd. All rights reserved.