The paper summarizes the results of a large European project on the critical risk factors for Power-Two-Wheeler (PTW) safety. Analyses conducted in both a macroscopic and microscopic level in Greece, Spain, Italy, Great Britain, Austria, Finland and Germany revealed a set of critical risk factors as well as their ranking of importance. Among the research questions treated are what are the most relevant PTW accident configurations at European level and why accidents of those configurations take place. The identified critical risk factors cover a widerange of interactions and form important knowledge for structuring guidelines dedicated to PTW users. Moreover the analyses conducted add value to the mannerfuture in depth analyses and accidentology studies should be conducted.