Professor Chris Rissel writes:

The ongoing bicycle helmet legislation debate usually focuses on how effective helmets are, and whether rates of head injury among cyclists have changed due to helmet legislation.

However, while injury prevention concerns are important, the other side of the issue is whether helmet legislation deters people from cycling, and then missing out on the health benefits of being more physically active.

A new research study by myself and Dr Li Ming Wen at the University of Sydney, published in the Health Promotion Journal of Australia, found that one in five adults say they would cycle more if they didn’t have to wear a bicycle helmet.

When mandatory helmet legislation was introduced in Australia in 1991, observational studies of the number of people cycling found that there was about a 30-40% drop in the number of people cycling. There were even larger drops in some groups, such as adolescents. When similar legislation was introduced in New Zealand in 1994, the same marked drop in cycling participation was observed.

Having seen what happened, most of the rest of the world did not follow suit. Mexico City and Israel recently repealed bicycle helmet legislation that they had introduced but not enforced, primarily to make their bicycle share schemes viable.

Twenty years on, is mandatory bicycle helmet legislation still holding back cycling in Australia? 

The Census data for how we travel to work gives one stable measure of cycling since 1976 (even if it dramatically under-reports cycling). It tells us that the proportion of workers using a bicycle to get to work has been at about 1% for the past 25 years. There was even a slight decline in 1991 (down from 1.1% to 0.9%) where it stayed until 2006, before going back to 1.1%.

Would people ride more if they didn’t have to wear a helmet?

The answer is yes. One in five (22.6%) say they would ride a bicycle more if they didn’t have to wear a helmet, particularly occasional cyclists (40.4% of those who had cycled in the past week and 33.1% of those who had cycled in the past month). Of those who hadn’t ridden bike in the past year 19% said they ride more.

While a hypothetical situation, if only half or a quarter of the one in five respondents who said they would cycle more if they did not have to wear a helmet did ride more, Sydney targets for increasing cycling would be achieved by repealing mandatory bicycle helmet legislation. This increase in cycling would result without having to spend millions of dollars on new cycling infrastructure.

Here is some basic maths to help justify this claim.

There are about 3.5 million people in Sydney aged 16 years and older. Conservatively 60% haven’t ridden a bike in the past year – leaving 2,100,000. With 19% of people not having ridden the past year saying they would ride more, this represents 399,000  potential riders.  In Sydney, the Census tells us that about 10,000 people rode to work on Census day.  We know that this is an under-estimate of cycling levels, but even if we multiply this by a factor of 10 this 100,000 Sydney cyclists are still a quarter of the potential new cyclists.

A significant proportion of the population would continue to wear helmets even if they were not required to do so. Almost half (47.6%) of respondents said they would never ride without a helmet, 14.4% said “all the time”, 30.4% said “some of the time” and the rest were not sure. Infrequent riders were most likely to say they would wear a helmet.

Overall, one third of respondents did not support mandatory helmet legislation. There was an inverse association between riding frequency and support of the helmet legislation, with those not riding in the past year most likely to support helmet legislation, and more frequent riders less likely to support it.

So the non-riders (inexperienced majority) are happy to impose the mandatory helmet legislation on ‘other people’ – it doesn’t affect them.

• Chris Rissel is from the School of Public Health at the University of Sydney

• Previous Croakey posts on the bicycle helmet debate.