Forget your helmet - wear a wig . . . Two weeks ago, On Yer Bike looked at making cycle helmets mandatory. This week, the problem with cycle helmets, full stop: why it's safer to cycle without.

I do usually wear a helmet around town, and always when mountainbiking. Once, I was doing just 15mph down a steep, root-strewn trail when I overdid the front brake and cartwheeled head over heels into a stout trunk - head first. My head ached a lot and my handlebars were twisted, but I survived "thanks to the helmet". When going to the pub, I always wear a helmet. Any cyclist knows the danger of a few "go-faster" pints at the end of a long working week. They're called "go-faster" for a reason. I was on my racing bike slipstreaming a bus along Cowley Road.

A young man in a souped-up car wanted to tailgate the bus as well. He honked, but I was enjoying tailgating the bus, so I didn't let him past. I looked behind at the boy racer. When I turned round, the bus was at a standstill five metres in front of me. I hit the brakes hard at 20mph. I didn't hit the bus but, in another case of unexpected cartwheeling, my helmeted head met the ground. I was bruised and embarrassed, but alive.

If you're going to cycle like an idiot, wear a helmet. But if you cycle in a normal fashion, I don't think there's much point, unless you are a child. Helmets are a good idea for children because they fall off a lot at low speeds.

My opinion is backed by Dr Ian Walker, a traffic psychologist from Bath University. He rode a bicycle fitted with an ultrasonic distance sensor to record data from more than 2,500 overtaking motorists in Salisbury and Bristol. He found that drivers pass more closely when overtaking cyclists wearing helmets than bare-headed cyclists, increasing the risk of a collision with the helmeted cyclists.

Dr Walker spent half the time wearing a cycle helmet and half the time bare-headed. He found that drivers were twice as likely to get too close to the bicycle when he was wearing the helmet.

He said: "This study suggests wearing a helmet might make a collision more likely in the first place. We know that many drivers see cyclists as a separate subculture, to which they don't belong. As a result, they hold stereotyped ideas about cyclists, often judging all riders by the yardstick of the lycra-clad street-warrior. This may lead drivers to believe cyclists with helmets are more serious, experienced and predictable than those without, so drivers leave less space when passing."

He found that buses and trucks passed considerably closer than cars when overtaking cyclists. He was actually struck twice during the experiment, by a bus and by a truck, and he was wearing a helmet both times.

But this is the best bit: Dr Walker then donned a long wig to see whether there was any difference in passing distance when drivers thought they were overtaking what appeared to be a female cyclist. While wearing the wig, drivers passed him with an average of 14 centimetres more space. That's it - I'm binning the battered helmet and getting myself a long, curly wig.