Cyclists Gillian McDonald and Tony Anderson think their helmets saved their lives. When they were hit by a car in Sydney, their helmets were destroyed.

It could have been their heads.

But do compulsory helmet laws do more harm than good?

A disclaimer: I am a cyclist. I ride a bike to work in Sydney I rode for ten years when I lived in London.

Which city do I feel safer cycling in? London.

Why? There are far more bikes there than there are in Sydney, and there's safety in numbers. Drivers understand how to deal with bikes and don't crash into them. 

I'm a driver as well as a cyclist. I know bikes present challenges. But practice makes perfect.  Australian drivers haven't had enough practice, because there aren't enough bikes. 

Compulsory helmet laws are at least partly to blame.

There have been many studies some recommend a trial relaxing the law for adults on Queensland’s quieter roads. The University of Sydney and the British Medical Journal also weighed in on the subject.

Helmet laws reduce spontaneous journeys by bike.  Not all rides are fast, or on main roads. Sometimes they're just a few hundred metres along a local street to buy milk.  When – to cycle – a helmet needs to be found, a journey that might have been made by bike is done on foot or, worse, by car.

Also, mandatory helmet laws suggest cycling is more dangerous than it is. So fewer cycle, because they fear the exaggerated consequences.

There have even been studies that show cars are driven closer to bikes where riders are wearing helmets drivers perhaps subconsciously think the harm they could do will be less if they hit a helmeted rider.  Other studies show bike riders with helmets ride more dangerously than ones without - if they crash, they reason, they’ve got protection.

Finally, when more people cycle, more have an interest in safer cycling infrastructure.  Planners and politicians respond.

These are well-established arguments. They're why only New Zealand has copied Australia's mandatory helmet laws. Other countries have considered them, and rejected them – citing the Australian experience: Australia is the only developed country where the number of cyclists is falling, but the number of cycle deaths is rising.

These arguments, though, seem outlandish to Duncan Gay, New South Wales' Minister for Roads. His full, unedited, interview with me is posted here. (The discussion on helmets starts exactly four minutes in.)

An Australia without mandatory cycle helmets would be, Gay says "Free willy rage everywhere hav[ing] anarchists run the world.”

He makes the comparison between helmet laws and seat-belts laws. The difference, of course, is that the world has copied Australia on seat-belts. Other countries cite Australia as an example of what not to do with helmet laws.

Duncan Gay rejects that. He's not a cyclist himself, he says, but he supports cyclists – even though he'd like to see more fined, and taken off the road. 

Gay is considering compulsory cyclist licenses: a world first. His reasoning is that sometimes cyclists break road rules: jumping red lights, for example. He wants them punished.

Some cyclists, of course, say that the rules are written for drivers and shouldn't apply equally to cyclists: when they break rules they normally do so to minimise danger, not exacerbate it. For a vulnerable cyclist, slowing at a junction, checking no traffic's coming and then going through a red light is safer than waiting for accelerating cars and trucks to pull off all around.   

Cycle licenses would be another barrier-to-entry to potential cyclists, and would clear some existing cyclists off the road. They'd be a further fall in the number of cyclists and an increase in danger for those who continued to ride. 

Australian politicians are in a bind, though. Any who relaxed laws would face the prospect of a tabloid news crew turning up if a helmet-less cyclist were killed. And Australia is a drivers'-democracy. Most don't cycle, and get annoyed by those who do.

Nor is the cycling community united.  Sports cyclists – who go fast, often on main roads and already take with them plenty of specialist kit - generally favour mandatory helmet laws. But cyclists who use bikes for transport - for getting from A to B - generally agree: more bikes makes cycling safer remove all the barriers-to-entry you can.

I'll continue to wear a helmet. It could – one day – save my life.  The evidence suggests, though, that mandatory cycling laws are not good for cycle safety as a whole.