The first SUNflower report showed that risks are also highest in Britain for motorcyclists, when mopedists are excluded. The extended study will investigate whether accidents involving motorcyclists occurred in different circumstances (eg single vehicle, urban/rural, hitting different roadside objects, on roads with similar speed limits, involving similar other vehicles) to the other countries, and whether the motorcycling population was different. If differences are found, we will try to assess to what extent these are affected by exposure, and to what extent by driver or rider behaviour, or by different road design.