Wearing a helmet is the most effective method of reducing head injuries and fatalities resulting from motorcycle crashes.  Research has shown the motorcyclists who are not wearing a helmet are four-times more likely to sustain head injuries and ten-times more likely to have brain injuries in the event of a crash than someone who was wearing a helmet. (Yu, W.-Y., C.-Y. Chen, W.-T. Chiu, and M.-R. Lin. “Effectiveness of Different Types of Motorcycle Helmets and Effects of Their Improper Use on Head Injuries.” International Journal of Epidemiology 40, no. 3 (June 1, 2011): 794–803. doi:10.1093/ije/dyr040)