Fairfax cycling columnist Michael O’Reilly revived the debate about bike share schemes and mandatory helmets last week with a new article, Share bike schemes need to lose the lids.

He reckons bike share is flourishing everywhere in the world except Australia, where Melbourne Bikeshare and Brisbane’s CityCycle are performing very poorly. Were they to close, it “would be a disaster for our urban spaces”, he warns.

What distinguishes these two schemes from virtually every other one in the world is they mandate riders must wear a helmet. That, O’Reilly suggests, is why they’re failing.

The key solution he advocates is to exempt bike share from the helmet law.

I don’t think there’s any doubt that patronage of these two schemes is affected by the existing law. If the “cost” of any activity is raised — in this case principally by the difficulty of getting access to a helmet — demand will fall.

Equally, there’s no doubt that exempting bike share from the law would be a controversial step. While those who would defend the law are relatively quiet now, I expect their resistance would be strident if they thought there was a clear and present prospect of the law being diluted.

They would perceive a permanent exemption for bike share as tantamount to doing away with the law for all cyclists. They’d see it as the thin end of the wedge and I think they’d be right. Granting an exemption would amount to saying the law should be repealed for everyone (every adult anyway).

There’s a respectable argument for doing away with the law in its entirety and there should be a full and wide ranging debate about that in each state. But seriously weakening the law on the narrow grounds that it would increase use of bike share is a much more doubtful proposition.

I think there are several important issues that would need to be thought about in the context of any serious proposal for excepting bike share in Victoria and Queensland from their respective helmet laws.

Even if the law were absent, it doesn’t automatically follow that Australian bike share schemes would flourish. There’s a range of other factors that might also suppress use.

For example, in Melbourne there aren’t enough bike stations, the tariff structure is unfriendly to tourists and there are alternative travel options such as trams. Safety is another key explanation for the low take-up of bike share.

Infrastructure is inadequate and a lot of drivers are unsympathetic toward cyclists. Too many potential bike share riders don’t feel safe on the roads, especially those who aren’t regular riders.

O’Reilly’s contention that bike share schemes elsewhere are universally a “success” is undemonstrated. There are currently 165 cities worldwide with bike share.

Advocates tend to focus on a limited number of high-profile implementations, like Paris, London and Dublin. What’s missing is an objective standard of what constitutes “success”.

Even if there were such a criterion, there’s little independent, rigorous evidence on how this multitude of other schemes is faring. Are they all a “success”?

Since bike share schemes in Australia are publicly funded, it’s critical to ask what the overall social benefits are. It’s also important to ask who receives those benefits.

If bike share mostly replaces public transport trips and induces trips that wouldn’t otherwise be made, then the environmental case for public subsidy isn’t compelling. If the primary beneficiaries are relatively well-off inner-city residents and CBD workers, the equity implications aren’t persuasive either.

Were Melbourne Bikeshare and Brisbane CityCycle to close it would be regrettable, but it wouldn’t be “a disaster for our urban spaces” as O’Reilly predicts. Paris was a delightful place before bike share and still would be without it, as would Melbourne.

Bike share can enhance an already vibrant city, but it’s not a necessary condition. Nor is it likely bike share can turn a run-of-the-mill city into a vibrant one. Terms such as “disaster” are excessive.

Many bike share advocates are against compulsory helmets for adult riders, but most of the population assume the law has a net community health benefit. If the latter are right, exempting bike share would impose a social cost and could undermine the standing of the wider law.

So when I weigh it up, it doesn’t seem that the survival of bike share is so important that it justifies effectively abandoning the current law on helmets. Whether or not the helmet law is “right”, it is a major issue of policy and any proposed change requires serious debate and public involvement.