No, sorry, this is not what has happened. The only places where real and relatively reliable figures are available are Australia and New Zealand. Introducing mandatory helmet laws reduced the number of cyclists, possibly because some people just didn't want to wear one, possibly because their introduction sent a message that cycling is dangerous. Yet the number of head injuries did NOT fall faster than the number of cyclists fell. In fact, in New Zealand I think I am right in saying that the biggest decline in head injuries to cyclists took place before the helmet law was introduced.

I have yet to hear a response to the question of head injuries to pedestrians. Given that the incidence of head injury to pedestrians per mile travelled is similar to that for cyclists (both groups get hit by cars) why, if it is common-sense to wear a helmet while cycling, aren't all you helmet-wearers wearing them while walking across the street?

Let's be clear. I am all in favour of helmets in certain circumstances. Young children learning to ride are the group most at risk of the sort of incidents where helmets are likely to help - low-speed falls with no other vehicle involved. Downhill MTB-ers are highly likely to come off at speed in potentially unforgiving terrain - full-face helmets are a good idea. And I'm all in favour of anyone who thinks they need a helmet, wearing one. But it does not follow that helmets are necessary for ordinary road cycling, or will significantly alter your already tiny chances of suffering a serious injury. So recognise that for the most part, while they may make you feel safer, they probably aren't doing much to help you be safer. And the subliminal message that is being sent - "cycling is dangerous and if you don't wear a helmet you might die" - is both inaccurate and has highly negative consequences; including, for example, fostering a belief that cyclists don't belong on the roads with other traffic.