It’s easy to see why.

When it comes to the health and safety of our cities, cycling is the most popular form of transport.

And while the health benefits of cycling have been recognised for decades, a new report by the University of Sydney says the cost of helmets is increasing faster than the overall cost of cycling.

“For every $1 invested in helmets, the health costs of cycling are about $1.70,” said Dr Michael O’Brien from the University’s Centre for Transport Research.

The study, which is published in the BMJ, found that the cost per kilometre travelled on a bicycle in Australia had increased by almost 100 per cent between 2000 and 2014.

Dr O’Brian said helmets cost about $130, which translates to about $200 per helmet.

“So that’s almost $1,000 a year for people,” he said.

“And we know that the health cost of injuries in cycling is about $500 per person, so if you put that on top of the cost, you get a total cost of $1 billion per year for cycling.”

The study also found that more than a quarter of cyclists were spending more than their lifetime average on helmets.

“We know that if you’re in a car, and the risk of being in a crash is much higher, then the money you’re spending on your helmet is actually going towards the risk mitigation strategy, and it’s not going to be going towards protecting your body from the road,” Dr O ‘Brian said.

The biggest health costs from cycling have to do with air pollution, Dr O O’Bryant said.

A significant proportion of helmets worn by cyclists were made of nylon or plastic, and Dr OBrien said that it was a “huge waste” to waste money on a product that “doesn’t contribute anything to public health”.

“The biggest cost to the public purse is the cost to health of those who are wearing them,” he added.

“That’s where you see the health-costs for cyclists that we’ve identified.”

Dr O Brion said the health impacts of the wear and tear of cycling helmets on the wearer were already known.

“If you’re wearing a helmet, you’re exposing yourself to a large number of toxic chemicals,” he explained.

“Those chemicals, as we know, have been linked to lung and heart disease and a whole range of things.”

‘Not the best fit’ Dr O Bryants study also looked at the health effects of helmets on cyclists.

“What we found is that, when you’re cycling, you tend to get a little bit of headwind,” Dr Bryants said.

“You get a bit of wind on your back, and you’re going to get headwind in the direction you’re travelling.”

So that will affect your ability to control your head, and that’s why a helmet can be really useful for cycling, because you can use that as a sort of protection from headwind, and not necessarily the wind itself.