The wearing of a motorcycle helmet certified to an appropriate standard has been the most significant step in reducing fatal and serious injury among motorcyclists worldwide. Motorcycle helmets have been shown to be at least 50% effective in reducing fatal head injury in motorcycle crashes [1]. Most motorcycle helmet standard requirements have remained substantially the same for 40 years, while over the same period our understanding of causes of injury to the brain has been rapidly improving. Current international motorcycle helmet standards are based around a translational acceleration energy attenuation test.

Reconstruction of crash involved motorcycle helmet damage in the COST 327 study [2] demonstrated that the AIS 2+ head injuries in helmeted head impacts are more likely to be due to indirect (or head motion induced) rather than direct impact. Occupants of crashed vehicles have also been observed by Gennarelli [3] to have a shift in the type of brain injury treated in the emergency room. This shift has been related to improvements in vehicle safety, especially the use of airbag technology. The improved protection for vehicle occupants in crashes due to airbag controlled head impacts has led to a decreasing incidence of focal (direct) brain injury accompanied by a relative increase in diffuse (indirect) brain injury. In sporting head injury, King et al. [4] have shown that football and bicycle helmets built to the current test requirements reduce translation acceleration of the head but do not necessarily reduce the rotational acceleration of the head of the wearer in an impact. These recent advances in our knowledge of the effects and causes of traumatic brain injury have yet to be carried over to motorcycle helmet standards.

The crash characteristics and injuries to the head sustained by helmeted motorcyclists were examined by reference to data from motorcycle crash studies including:​

• COST 327 [2], which reconstructed the helmet impact for n=226 motorcyclists with AIS 2+ head injuries;​
• MAIDS [5], which investigated n=921 injurious European motorcycle crashes;​ and,
• Gibson and Thai [6], which examined the helmets and injuries of n=175 riders in fatal motorcycle crashes in Australia.

The crash data regarding the head injury sustained in helmeted head impacts in motorcycle crashes suggests areas available to improve current motorcycle helmet effectiveness and motorcycle helmet standard test methodologies in reducing brain injury. This study defines some of these areas where motorcycle helmet effectiveness in preventing brain injury can be improved, including:​

• Changes to helmet test methodology to include biofidelic rotational as well as translational head motion effects to be measured;​
• Development of accepted test requirements to mitigate rotational brain injury, with initial emphasis on reducing traumatic brain injury TBI;​ and,
• Improved facial impact protection, without increasing neck injury risk.