University of New South Wales researchers have found that bicyclists who do not wear helmets are more likely to engage in risky riding behaviours and be involved in more severe crashes with cars and trucks than those who wear protective headgear.

This analysis involved a retrospective, case–control study using linked police-reported road crash, hospital admission and mortality data in New South Wales (NSW), Australia during 2001–2009. There were 6745 cyclist collisions with motor vehicles where helmet use was known. Helmet use was associated with reduced risk of head injury in bicycle collisions with motor vehicles of up to 74%, and the more severe the injury considered, the greater the reduction.

The case-control study was carried out by linking detailed information on admissions to all hospitals in NSW with police reports on road traffic collisions in which cyclists were injured or killed. One in four of the cyclists who crashed were not wearing a helmet.

Around one half of children and adolescents less than 19 years were not wearing a helmet, an issue that needs to be addressed in light of the demonstrated effectiveness of helmets. Non-helmeted cyclists were more likely to display risky riding behaviour, however, were less likely to cycle in risky areas; the net result of which was that they were more likely to be involved in more severe crashes.

In a press release the study co-authors, Dr Jake Olivier and Chair of Road Safety, Professor Raphael Grzebieta spoke about the effectiveness of bike helmets in preventing head injury, and about the need for mandatory helmet laws.

“The study evidence presented scientifically dismisses the absurd suggestion by anti-helmet law lobbyists that mandating helmet wearing makes cycling more dangerous overall, with no significant improvement in head injury rates or severity.” Prof. Grzebieta said. “It is a ‘no-brainer’ that helmets are very effective in preventing head injuries in cycle related crashes.”

Dr Olivier said, “The benefits of helmets were clear in this study. Cyclists without helmets had up to 3.9 times the risk of sustaining a head injury, compared with those who wore helmets. The more severe the injury, the greater the benefit: Helmet use reduced the risk of moderate head injury by 49 per cent, of serious head injury by 62 per cent, and of severe head injury by 74 per cent”

They both noted there has also been speculation that wearing helmets is associated with riding more recklessly, because cyclists feel protected, but the study found the opposite was the case.

“Non-helmeted cyclists were almost three times as likely to have disobeyed traffic controls as helmeted riders, and more than four times as likely to have been above the blood alcohol limit,” Dr Olivier said.

About half of the children and adolescents less than 19 years old who were injured in a collision were not wearing helmets, compared with only 15 per cent of 30 to 39 year olds.

“This issue needs to be addressed through much stronger enforcement of the helmet law and wider education in light of the demonstrated effectiveness of helmets,” Dr Olivier and Prof Grzebieta said.

We’ve seen other theories that take an opposite point of view than this study. There is the “risk compensation theory” that hypothosises, “the behaviour of cyclists change as a consequence of wearing a helmet in ways that offset the protective benefit of helmets in accidents.” There is also the view that motorists are much less cautious around cyclists who are wearing helmets.

Personally, I’ve changed my view on the helmet debate. I’m quite comfortable riding a utility bike without a helmet as I believe the risk is minimal and the benefits far outweigh the danger. But, riding a road or mountain bike without a helmet? Forget about it. Unfortunately we don’t have a choice in Australia. The current fine in Victoria is $176 if you’re caught not wearing a helmet.

The UNSW study was led by Dr Mike Bambach and Dr Rebecca Mitchell and conducted by researchers in the UNSW Transport and Road Safety Research group and School of Mathematics and Statistics. It was published yesterday (Feb4, 2013) in the journal Accident Analysis and Prevention. Unfortunately I cannot post the study in full because of journal rights.