This puts B.C. in the same Draconian league as Ontario, which will begin enforcing North America's first universal bicycle helmet law on Oct. 1. Manitoba and several U.S. states require helmets on children under 14 or 15; Ontario is singular in treating all its citizens as if they were children. (Australia is the only other place in the world where the simple act of riding a bicycle is considered so hazardous as to require adults to don protective gear.)

For Ontario legislators, the need for such extraordinary measures was self- evident. "We in Ontario just know that kids are getting hurt in vast numbers," declared Tory MPP Dianne Cunningham when she introduced the law in 1993. NDP Transport Minister Gilles Pouliot agreed, noting "with all the evidence showing how much extra protection a helmet offers, why take a chance?" The bill passed, as these things do, with unanimous support.

Which suggests that maybe this matter did not receive quite the degree of scrutiny it deserved. In fact, there are no data on the prevalance of head injuries among the province's cyclists. The closest approximation is a 1995 study, based on coroners' records, of bicycle fatalities in the province from 1986 to 1991. Of the 212 cyclist deaths in that six-year period, the study's authors find that three- quarters were caused by head injury: an average of 26 per year.

This is roughly in line with larger U.S. studies, which also show a ratio of about 300 bicycle-associated head injuries, from scrapes to fractures, to every one that is fatal. (Head injuries, in turn, account for about a third of all bicycle injuries.) The same ratio would indicate that Ontario's cyclists suffer roughly 8,000 head injuries a year.

Do these figures suggest cycling is a particularly risky endeavour? Not when you consider the enormous numbers of cyclists who don't hurt their heads. A 1992 Ministry of Transport survey found the province had about 2.5 million active cyclists, defined as those who ride their bikes at least once a week. That puts the incidence of head injuries at about 32 for every 100,000 active cyclists; the number of cycling deaths due to blows to the head is just 1 in 100,000. In other words, 99.999 per cent of Ontario's cyclists get through each year without falling on their heads and killing themselves. By way of comparison, there were 1,042 motor- vehicle traffic deaths in Ontario in 1992. There were more deaths from poison gas (28), falling out of a chair or bed (43), and choking on food (116) than from bicycle head injuries.

Suppose, as a conservative estimate, that each of those active cyclists rides an average of 150 kilometres a year: equal to about two trips a week, 1.5 kilometres there and back, from May to October. That works out to one dead rider for every 14.6 million cyclist-kilometres. Or to put it another way, the average cyclist would have to keep pedalling for 96,153 years before he was statistically likely to smash his head in. Of course, the odds of a non-fatal head injury are considerably shorter: one in every 47,500 cyclist-kilometres, or a little over three centuries of safe cycling for the average rider.

Fatal bicycle head injuries differ from other bicycle injuries in several respects. Most of those killed on their bikes are adults, while most of those injured are kids. Fatal bicycle injuries are almost always (more than 90 per cent) the result of a collision with a car, while lesser accidents usually have other causes. And while helmets may, as studies show, reduce the risk of head injuries in most other accidents by as much as 85 per cent, the same cannot be said of the more severe accidents that produce fatal head injuries. (The efficacy of helmets may be overstated in any case. Few cyclists - less than 10 per cent - wear them. It may be that the sorts of riders who do wear a helmet are more safety-conscious to begin with.)

But isn't any reduction in injuries and deaths worth any expense? Well, no. The costs of mandating helmets is measured not only in dollars but in lives. The added nuisance of finding and wearing a helmet will cause a certain number of bike trips to be replaced with car trips: in the two states in Australia where such laws were enacted, bicycle use dropped 25 per cent. That means more chance of auto accidents, and fewer health benefits from cycling.

Then there is the opportunity cost: The millions of dollars cyclists will have to shell out for helmets to protect them in the event of an accident might be better spent on measures, such as bicycle lanes, that would prevent accidents from taking place. And whatever revenues the $90 fines for non-compliance may yield, they can hardly cover the costs of sending Ontario police chasing after 2.5 million cyclists.

If there is a case for helmet laws, then, it would seem to apply mostly to children, who are more likely to encounter the kinds of accidents where a helmet might do some good. The massive head injuries that adults are prone to suffer may be responsible for most bicycle fatalities, but these are few in number and the likelihood of helmets preventing them is small. A helmet law that applied only to children would therefore seem more cost- effective. It would also accord better with the values and principles of a free society.