Riding Without a Helmet is Dangerous Overview

First, it is the best protective gear you can wear while riding a motorcycle. Think of it at the same time you think of your ignition key: Pick up the key; pick up the helmet. They go together. Helmet use is not a “cure-all” for motorcycle safety, but in a crash, a helmet can help protect your brain, your face, and your life.

Combined with other protective gear, rider-education courses, proper licensing and public awareness, the use of helmets and protective gear is one way to reduce injury.

You hope you never have to “use” your helmet, just like you hope you won't ever need to “use” the seatbelt in your car. But crashes do happen. We can't predict when or what kind they will be. You should not say to yourself,” I’m just running down to the store,” and not wear your helmet. In any given year, a lot of people make good use of seatbelts, and a lot of riders give thanks that they were wearing helmets.

Second, a good helmet makes riding a motorcycle more fun, due to the comfort factor: another truth. It cuts down on wind noise roaring by your ears; on windblast on your face and eyes, and deflects bugs
and other objects flying through the air. It even contributes to comfort from changing weather conditions and reduces rider fatigue.

Third, wearing a helmet shows that motorcyclists are responsible people; we take ourselves and motorcycling seriously. Wearing a helmet, no matter what the law says, is a projection of your attitude
toward riding. And that attitude is plain to see by other riders and non-riders alike.

To understand the action of a helmet, it is first necessary to understand the mechanism of head injury. The common perception that a helmet's purpose is to save you from splitting your head open is

misleading. Skull fractures are usually not life threatening unless the fracture is depressed and impinges on the brain beneath and bone fractures usually heal over a relatively short period. Brain injuries are much more serious. They frequently result in death, permanent disability or personality change and, unlike bone, neurological tissue has very limited ability to recover after an injury. Therefore, the primary purpose of a helmet is to prevent traumatic brain injury while skull and face injuries are a significant secondary concern.

The most common type of head injury in motorcycle accidents is closed head injury, meaning injury in which the skull is not broken as distinct from an open head injury like a bullet wound. Closed head injury results from violent acceleration of the head that causes the brain to move around inside the skull. Think of how you lurch backwards and forwards while standing on a bus as it accelerates or stops. During an impact to the front of the head, the brain lurches forwards inside the skull, squeezing the tissue near the impact site and stretching the tissue on the opposite side of the head. Then the brain rebounds in the opposite direction, stretching the tissue near the impact site and squeezing the tissue on the other side of the head. Blood vessels linking the brain to the inside of the skull may also break during this process, causing dangerous bleeds.

Another characteristic, susceptibility to shearing forces, plays a role primarily in injuries that involve rapid and forceful movements of the head, such as in motor vehicle accidents. In these situations rotational forces such as might occur in whiplash-type injuries are particularly important. These forces, associated with the rapid acceleration and deceleration of the head, are smallest at the point of rotation of the brain near the lower end of the brain stem and successively increase at increasing distances from this point. The resulting shearing forces cause different levels in the brain to move relative to one another. This movement produces stretching and tearing of axons (diffuse axonal injury) and the insulating myelin sheath, injuries that are the major cause of loss of consciousness in a head trauma. Small blood vessels are also damaged causing bleeding (petechial hemorrhages) deep within the brain. It is clear then that it is very important that the liner in a motorcycle helmet is soft and thick so the head decelerates at a gentle rate as it sinks into it. Unfortunately, there is a limit to how thick the helmet can be for the simple reason that the helmet quickly becomes impractical if the liner is more than 1 or 2 inches thick. This implies a limit to how soft the liner can be. If the liner is too soft, the head will crush it completely upon impact without coming to a stop. What happens then? Well, beyond the liner is a hard plastic shell and beyond that is whatever the helmet is hitting, which is presumably an unyielding surface. The head cannot move any further so after crushing the liner it comes suddenly to a dead stop, causing high accelerations that injure the brain.

The increase in motorcycling has focused attention on injuries sustained during these activities. Most of these injuries are traumatic brain injuries (TBI), caused by the lack of rider head protection. This exposure of the rider accounts for the particular types of injuries seen during these activities.