basingstoke123 » Mon Sep 28, 2009 10:04 pm wrote
"The most likely explanation for the increase in the accident rate in Australia is the 'safety in numbers' effect "
It is correct to say safety in number has an effect, however there is evidence to point to helmets having an effect.
The petition to the Victorian Parliament mentions a 119% increase in accidents for adults prior to legislation
... 991+%29%0a )
some of the increase most likely due to the increase in cycling but helmet use was also increasing.
Thompson's paper 1989 mentions the wearing rate was low generally (possibly about 7%) but details about 23% of the emergency room and 23% of the population control group were wearing them. see Clarke CF, The Case against bicycle helmets and legislation, VeloCity Munich, 2007. http://www.ctcyorkshirehumber.org.uk/campaigns/velo.htm
for more examples.
The safety in numbers explanation allows helmets to be promoted but also allows legislation to be opposed. Some of the evidence points to helmets contributing to increasing accidents in addition to safety in numbers effects after helmet laws.
If anyone can prompt skiing and snowboarding and cycling research to measure the head accelerations levels involved in each activity this could be useful. Cycling has been measured (in about 1986) at about 10g for hitting deep pot-holes. This is probably the main reason why bike helmets have to be so much lighter than motorcycle helmets. Clarke 1995 Safer Cycling publication provided figures comparing the two groups. The 10g force from a helmet making it more difficult to maintain balance when hitting pot-hole type situations.
Injuries to that part of the head where helmets offer protection are roughly 10%+, face injuries 20%+, meaning other injuries, arms , legs etc are about 60%-70%. Any increase in accidents results in more injuries, even if helmets provide some protection.