Why should you wear a helmet?

The inner padding of the helmet is what keeps you comfortable and makes the helmet fit snugly. This is not only important for your comfort, but reduces the movement of the head inside the helmet - also important in an accident. Any experienced rider would notice that the liner fits less snugly with time, as it degenerates because of compression and sweat damage, and sometimes washing (if it is a removable liner, of course).

Differences of opinion arise in the construction of the impact-absorbing liner. How hard or soft should the liner be made? A certain stiffness of the liner is required by the Snell Memorial Foundation - one of the premier organisations involved in the rating of helmets. Together with the Department of Transport rating, it is generally perceived that having a Snell rating on your helmet is a good thing. However, their standards have been criticized in an article in Motorcyclist magazine, where it was asserted by some that a softer liner would lead to less force being transferred to the head of the motorcyclist. One would think that some sort of gel-like substance in the helmet would work better, but a substantially heavier helmet would unfortunately not be safer, and would certainly cause more neck injuries. More studies need to be done on this, to settle the argument once and for all. Myself, I'm waiting for a helmet constructed using carbon nanotubing...
 

But let us get to the statistics of helmet use. There are studies out there which imply that a helmet makes no difference in fatality rates, and merely trades head injuries for neck injuries. See, for instance, the Goldstein study. His article does raise some interesting points, such as the fact that helmeted riders (where wearing a helmet is an option) tend to be more risk-averse, hence more likely to have lower impact speeds when involved in an accident and less likely to be under the influence of alcohol. This is an excellent point, but, I think, should be balanced with the tendency of greater safety measures in cars and motorcycles to increase risk-taking by the driver or motorcyclist. Although the Goldstein study has been used to argue against mandatory helmet use in Alberta, his methodology is disputed in a paper by Bedi.

 

The study conducted by Ouellet and Kasantikul concludes that wearing a helmet vastly improves the chance of survival. In certain cases, the helmet does not make a difference at all, simply because under extreme conditions there is no way to survive (picture riding into a brick wall at 200mph). As with the Goldstein paper, they reference the study done in California. Known as the Hurt study, this seems to be the most comprehensive study ever done on the topic. Studies done since then only seem to back up the conclusions of the Hurt report. So, what do they say? Stay tuned for a condensed version of the salient points.