With at least four different safety standards for street motorcycle helmets and different expert opinions from engineers, it’s extremely difficult for anyone to decide what kind of motorcycle helmet to buy. In fact, some notable experts such as Dr. Harry Hurt have said that the Snell M2000 and M2005 standards are “a little bit excessive.” It does appear that no matter which helmet you buy, any motorcycle helmet meeting at least the “entry-level” US DOT standard FMVSS 218 will provide significant protection. In fact, maybe even better protection than some more expensive helmets. Dr. Hurt believes that a motorcycle helmet meeting the Snell standard is too stiff possibly resulting in diffuse brain injuries and he is more interested in reducing the G. forces.
When considering prevention of brain injury, probably the most important part of the motorcycle helmet is the interior lining which absorbs most of the energy. When your head hits a hard object like the road or a car, the outside of your helmet stops instantly while your head keeps traveling until slowed by the inner liner and finally stopped by the outside shell of your helmet. The inner liner made of EPS (expanded polystyrene) absorbs a predictable amount of energy while it crushes, without springing back so your brain doesn’t get bounced back and forth. An “entry-level” US DOT standard FMVSS 218 motorcycle helmet will provide this protection.
The Hurt report found, not surprisingly, that the most deadly injuries to motorcycle accident victims were injuries to the chest and head. The report also found that use of a safety helmet which complies with FMVSS 218 is the single most important factor in the prevention of head injury and that no element of accident causation was related to motorcycle helmet use. Motorcycle helmet use did not cause fatigue or any reduction of critical traffic sounds or pre-crash visual field. Motorcyclists wearing helmets showed significantly lower head and neck injury for all types of injury, at all levels of injury severity and helmeted riders had less neck injuries than motorcycle riders without helmets.
In short, it appears that wearing any kind of motorcycle helmet meeting US DOT standard FMVSS 218 is a good idea. Whether you should be required to wear a motorcycle helmet is another matter.