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I can think of no reason why a well fitted helmet could cause more accidents

It's counterintuitive but there are possible reasons why a well fitted helmet would be more dangerous than no helmet:

Cycle helmets and rotational injuries

Minor head injuries are usually as a result of linear acceleration of the skull by impact with another object. Cycle helmets may produce benefit by reducing and spreading this force.

More serious injuries, on the other hand, are often as a result of angular or rotational acceleration, which leads to diffuse axonal injury (DAI) and subdural haematoma (SDH). These are the most common brain injuries sustained by road crash victims that result in death or chronic intellectual disablement.

Cycle helmets are not designed to mitigate rotational injuries, and research has not shown them to be effective in doing so.

To the contrary, some doctors have expressed concern that cycle helmets might make some injuries worse by converting direct (linear) forces to rotational ones. These injuries will normally form a very small proportion of the injuries suffered by cyclists, but they are likely to form a large proportion of the injuries with serious long-term consequences. In this way helmets may be harmful in a crash, but this harm may not be detected by small-scale research studies.

Thorough treatment of this subject, with comprehensive references, is to be found in the following article:

Curnow WJ. The efficacy of bicycle helmets against brain injury.
Accident Analysis and Prevention, 2003,35:287-292.
See also

Assessment of current bicycle helmets for the potential to cause rotational injury

http://www.cyclehelmets.org/1039.html

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Most recreational bikers, at least, never ride at night. The range of conditions and types of bikers for whom helmet use is a net positive is undoubtedly broader than the advice to get a light

If you're riding in the daytime, you don't need a light. But, you don't necessarily need a helmet either. Wearing a helmet may be a slight net positive (I wear one on that basis) but it's more beneficial (from a public health standpoint) for 1 person to be visible riding at night than for multiple people to be riding with helmets.

by Falls Church on Jun 17, 2012 8:21 pm • link • report