Some of my greatest fears can be traced back to old Doctor Who episodes. Do you remember the one when the Daleks invaded London and turned the population into robots by clamping metal helmets on their heads?

I thought about that last week when I read of plans by the people in charge of our new Paris-style cycle-hire scheme to make users wear helmets.

That particular line had disappeared by later editions of the newspaper, so maybe it has been denied; I hope so, for I can think of few things more likely to strangle the scheme at birth.

Cycle helmets stir strong emotions. I cycle daily and never use one; when I mentioned this last year, I got several emails scolding my irresponsibility.

Typically my correspondents would describe how they or friends had suffered accidents and "would not be alive today" without their helmets. As one put it: "Surely, common sense would tell you that if you are not wearing a helmet ... you are more likely to suffer a serious injury."

Common sense certainly would tell us this, but it also tells us that the world is flat; and alas, there simply is not, as far as I can trace, any good statistical evidence to back up the widely held common-sense belief about bike helmets.

There are, for sure, some small-sample studies (of, for instance, admissions to particular casualty wards) which show minor safety benefits. But the tiny sizes of these samples produce inevitable distortions. No large-sample study helps helmet-wearing's case.

The clearest large-sample evidence is from before-and-after studies of places, such as Australia, which made helmets compulsory.

These show that for some Australian states and cities the injury rate - for all injuries and for head injuries, minor and more serious  - actually rose after helmets became universal. In other states, there was no significant change.

One indisputable effect of Aussie helmet laws, however, was to deter cycling. Like me, many Australians dislike wearing a helmet, and cannot be bothered to carry one.

They have stopped cycling as a result. That is why you sometimes hear that Aussie helmets reduced accidents. They did, but only because the number of cyclists fell. The number of accidents did not fall in proportion, which is why the injury rate went up.

Surely "common sense", that infallible guide, tells us that it at least cannot be more dangerous to wear a helmet? Well, there is something called "risk compensation" - the human tendency, conscious or subconscious, to take more risks when we feel better protected.

There's also some evidence that helmets can increase what are called "rotational" head injuries, increasing the head's impact with the ground; and that motorists give non-helmeted cyclists a wider berth.

Helmets are, at best, a distraction, of only minor relevance to safety. At worst, they're a disaster. They contribute to British cycling's biggest turn-off: its image as a dangerous pastime, suitable only for macho young people in armour.

In places where cycling is normal, like Germany and the Netherlands, families and pensioners ride without fear in ordinary clothes, and helmets are rarer than a Gordon Brown apology.

My Doctor Who analogy is not completely far-fetched. Our fetish for helmets shows how our bossy, meddling, save-us-from-ourselves society is robotising our brains just a bit.

Since I cannot possibly harm anyone other than myself by not sporting a helmet, whether I wear one or not must be nobody else's business. I reject this silly combination of nanny state and urban myth - and on my own head be it.

The following two pieces have been extracted from letters in CTC's 'Cycle' magazine May 2009

SHOULD CYCLISTS WEAR A HELMET?

Dr Ian Walker, a traffic psychologist from the University of Bath, did a study in 2006 using a proximity meter. He found that drivers overtaking cyclists passed an average of 8.5 cm closer to those wearing helmets. He also found that drivers gave him an extra 14 cm of room when he was wearing a long blonde wig, to make him look like a woman to a driver approaching from behind! 

Conclusion: It's safer (and probably cheaper) to wear a wig!

SHOULD CYCLISTS PAY ROAD TAX?

Damage to road surface naturally goes up rapidly with axle load, meaning that an HGV should pay a higher rate of road tax than a car. Refer to http://en.wikipedia.org/wiki/Gross_axle_weight_rating  (which gives damage proportional to the fourth power of the axle load). Comparing the weight of a single bike and rider with that of a car and passengers, a fair assessment for a bicycle would be around 2 pence per year.

Conclusion: A proof of payment that would be secure, and not have too great an overhead to manage, would be a second class stamp mounted in a tax disc holder, valid for 10 years! However, as cars with carbon emissions lower than 100g/km pay no road tax, bicycles should also be free. QED.