Bicycle injuries and fatalities are reported by the police to Statistics Norway. Fatality records from the police are then corrected with Vital Statistics records. However, there is no complete hospital recording that could provide more correct data for bicycle injuries. Bicycle injuries are underreported in official data. There is a nearly complete omission of single bicycle accidents. This disguises societal accident costs and curtails the identification of black spots and effective infrastructure improvements. This paper provides an estimate of total bicycle injuries in Norway and the total costs of these injuries. Application of case study hospital data from Norwegian towns enabled an estimation of the relationship between these data and the official data, including the distribution of injuries by severity. Costs were then assessed by applying official monetary values for given levels of injury severity. Total annual bicycle injury costs are huge, but these costs must be balanced against the benefits of bicycling, related to health and environment. Accident reporting and data should be enhanced to enable a reduction of bicycle injuries.