Helmets became compulsory in Victoria in 1990. Credit:Eddie Jim "We've got this strange Australian exceptionalism, I think because we're a long way away from everywhere else," Mr Todd says. "We sometimes think we're doing things right when we're actually quite on the wrong track." Mr Todd is president of Freestyle Cyclists, a small anti-helmet laws group that has organised a "helmet-optional" bike ride across Melbourne's inner north next Saturday. About 50 riders are expected to take part in the protest ride, a 45-minute amble via back streets and bike trails from Nicholson Street in North Carlton to the Abbotsford Convent. "We're not telling people they shouldn't wear helmets, we're saying they should have the choice," Mr Todd says.

Opponents of Australia's mandatory helmet laws point to evidence that cycling rates have declined per head of population since they were introduced in the early 1990s, which they argue is a poor public health outcome. Census data shows the proportion of Australians who cycled to work dropped from 1.1 per cent in 1991 to 0.9 per cent in the 1996 and 2001 censuses, before returning to 1.1 per cent in 2006. "Reasons for this are unclear, although a historical lack of investment in cycling infrastructure coupled with mandatory helmet legislation may have contributed," Professor Chris Rissel, a Sydney-based public health expert, wrote in a 2012 academic paper. Helmets became compulsory in Victoria in 1990, and cyclists without a helmet today risk a $186 fine. Australia's medical experts are emphatic in their view that mandatory helmet laws save lives and prevent serious injury.

This month the chief health officers from each state and territory issued a joint statement in support of the laws. Helmets reduce the amount of kinetic energy transferred to the brain in a crash or fall, the health experts said. "Brain injury caused by bicycle falls and crashes can result in death or catastrophic physical and cognitive disability," they said. The Royal Australasian College of Surgeons also supports compulsory wearing of bicycle helmets. "The brain has a similar consistency to firm jelly," trauma surgeon Christian Kenfield said.

"It's not designed to absorb the type of impact that occurs when the skull hits a hard surface. A helmet helps to absorb the energy from the fall and protect the brain from the full impact." VicRoads and TAC also oppose any change to the law. Samantha Cockfield, TAC's senior road safety manager, said repealing helmet laws would be inconsistent with the state's long-term goal of zero road deaths. "If we are to get to zero, we need everyone to make good choices on the roads, and for cyclists this means being visible and wearing a helmet so they can protect themselves when the unexpected happens," she said. But Troy Parsons, another Freestyle Cyclist member who will join Saturday's ride, has another health concern in mind that makes him prefer not to wear a helmet.

He has a history of skin cancer in his family, so wears a broad-brimmed hat for sun protection. He has also lived in several other countries and says the Australian insistence on bike helmets is "hysterical" compared with overseas attitudes. "In New York you can ride through Central Park, you can ride up and down the river, no one will go hysterical at you, here you're treated like a criminal," Mr Parsons says.