CYCLISTS who do not wear helmets are more likely to ride in ways that put them at risk, according to a study of more than 6700 bike riders who collided with motor vehicles.
The authors of the study say the evidence demonstrates the value of compulsory helmet laws, which some cyclists and researchers want repealed to try and increase the popularity of cycling.
Academics at the University of NSW's Transport and Road Safety Research Group and its School of Mathematics and Statistics looked at the relationship between the severity of cycling injuries on NSW roads and whether the bike rider was wearing a helmet.
The results, published on Monday in the journal Accident Analysis and Prevention, show that cyclists not wearing a helmet were almost four times as likely to sustain a head injury compared to those with head protection.
In part, this was because cyclists who were not wearing a helmet were more likely to engage in other behaviour that led to accidents: they were more likely to disobey traffic rules and more likely to be riding while drunk.
''Having an opinion is one thing, but if you are going to make policies, such as repealing mandatory helmet laws, you have to look at evidence,'' said a co-author of the study, Jake Olivier.
''The evidence says helmets work: they minimise the risk of injury,'' Dr Olivier said.
The study looked at 6745 cyclists involved in collisions with motor vehicles between 2001 and 2009. It linked information from hospital admissions to police reports on the incidents.
''As the severity of the injury increased the benefit of wearing a helmet increased, which is very hard to ignore I think,'' Dr Olivier said.
Results showed that cyclists without helmets were more than 3.9 times as likely to sustain a head injury to those with helmets. Helmets 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.
The usefulness of compulsory helmet laws is a controversial issue among cyclists, and has become a topic of academic debate, with two camps broadly represented by researchers at UNSW and Sydney University.
Chris Rissel, from Sydney University's school of public health, has argued compulsory helmet laws discourage cycling, denying the public the health benefit from a more active lifestyle.
Dr Olivier's co-author, Raphael Grzebieta, said the suggestion there was a benefit in repealing mandatory helmet laws was absurd.
Asked why cyclists without helmets appeared to take other risks, Dr Olivier said that while his study did not address this question, the answer might be: ''Someone who is willing to disobey the law by not wearing a helmet might be more willing to disobey other laws.''
The story Cyclists without helmets 'likely to be risk takers' first appeared on The Sydney Morning Herald.