With the remarkable increase in the prevalence of obesity in the USA and most high-income countries of the world over the last 20 years, there is an urgent need to promote an increase in physical activity by persons of all ages. One of the methods to do so is the use of bicycling for both commuting and recreation. Bicycles were introduced in the 19th century and now number about 1 billion worldwide, twice as many as automobiles.1 It is the sharing of the road that can be problematic. About 900 deaths occur annually for cyclists, and most deaths from bicycle-related injuries are caused by collisions with motor vehicles.2 3 Head injury is by far the greatest risk posed to bicyclists, comprising one-third of emergency department visits, two-thirds of hospital admissions, and three-quarters of deaths.4 Since 1999, in the USA, the number and rate of bicycle-related deaths has decreased for those aged 16 years or less from 213 (0.31 per 100 000) to 118 (0.17 per 100 000) in 2007.2 The number and rate of cycle-related deaths for those aged 17 or more, …