Bobsledding is an exhilarating but dangerous sport in which teams of two or four athletes make timed runs down narrow, twisting, banked, iced tracks. Aerodynamic hulls are mounted on steerable, sledlike runners that move the athletes downhill at speeds of up to 145 km/h. Early racers bobbed their heads up and down to increase speed. The trick didn’t work but the name ‘bobsled’ has remained.