It's easy to quote dozens of "I fell off and might have had brain injury if I wasn't wearing a helmet" stories, we all probably know somebody, who knows somebody else to whom this happened.
Does this mean that bicycle helmets make you safe? No, in fact the guy in the film is right, it doesn't.
Now, before all the howls of anguish start up, I will say right out that anything that protects your head from damage is a good idea. I am not anti-helmet use, if that's what people choose to do. What I would like to try and bring in to the discussion is a bit of balance. Right at the start of that video the guy mentioned fear and risk. These are really, really important factors.
Some of my ex-colleagues in defence research have spent years studying risk and fear, and protective clothing, too. There is one human attribute that is hard-wired in that needs to be taken account of, it's something that we've inherited through evolution as a means to keep us safe. Each and every one of us has a "personal acceptable level of risk". By that I mean that we will all feel happy to accept some risk but will have a point where we decide a risk is unacceptably high and will refuse to accept it. This varies from individual to individual, has evolved to be higher in men than in women (hunters need to accept greater risk than carers) and is something we can't get rid of as it acts at a sub-concious level.
In modern life this "personal acceptable level of risk" shows in different ways to when we were living in less civilised times, when the environment, attack from predators, or other humans, was an everyday threat. A good example is driving a car. Most of us will have an open road cruising speed that we feel comfortable with. What we're subconsciously doing is driving at a speed where we're happy to accept the risk of losing control, collision or whatever. Some of us will drive faster than others, because we have a fair variation in that "personal acceptable level of risk" from one individual to another. If we exceed our acceptable level of risk we start to feel uncomfortable, we may grip the wheel more tightly, need to concentrate harder and find it difficult to do other tasks at the same time, like having a conversation or tuning the radio. Most of will have felt the "in the groove" feeling you get when you're in that risk comfort zone at some time, I'm sure.
OK, so what's this got to do with wearing a bike helmet? The answer is a rather bizarre phenomenon called risk compensation. In its basic form this tends to make us want to maintain the "personal acceptable level of risk" at a personal set point for the activity we're engaged in. One odd side effect of this is that if you make the perception of risk lower, you change behaviour to increase risk-taking and bring the "personal acceptable level of risk" back to its set point. The best proven example is car seat belts. In this country the use of 3 point seat belts were made a legal requirement around 27 years ago. The immediate effect was as expected, deaths and serious injuries to car occupants was reduced. However, over the next few years statisticians started to see a big increase in the number of deaths and injuries occurring to pedestrians and non-car driving road users. What had happened was fairly simple, if not at all obvious at first. Car drivers were bombarded with information that seat belts made them safer, so they started to feel far more safe in their cars than they had previously. This then subconsciously caused them to take more risks in order to get back to that infamous "personal acceptable level of risk". As we've gone on to add more and more safety systems to cars, pedestrian and other road user injuries have continued to climb. Some wags have suggested that the way to get car drivers to be more risk aware is to mandate the fitting of a 6" steel spike to the centre of the steering wheel and remove the drivers seatbelt. There's no doubt that most drivers would slow right down and drive more cautiously if this were mandated, again because of this bizarre risk compensation function we all seem to have to some degree.
My major concern over bicycle helmets is that, whilst some are pretty good, the majority are little more than a fashion statement. Most urban cyclists around the world travel at speeds little different to a jogger, so logic suggests that if we are going to mandate the wearing of helmets it should just be for cyclists, but for joggers and runners too. I used to ride a motorcycle without a helmet, when it was legal here to do so. I joined the Motorcycle Action Group here (once chaired by my ex-wife, as it happens) to protest against the helmet law 40 years ago. I wouldn't even dream of not wearing a motorcycle helmet now; as I've got older my "personal acceptable level of risk" has dropped to a lower level than it was when I was a teenager. I choose not to wear a bicycle helmet, although that may change as I get older. At the moment, riding around a fairly quiet rural area at modest speeds I don't feel any need to wear one, plus I think the current drop of designs are fairly unattractive and of dubious protective value (a view shared by my ex-colleagues who designed soldiers head gear). The majority seem to be a masterpiece of fashion marketing and are simply a way of trying to extract money from consumers with over-stated risks and protection factors.
As long as we have robust and honest information on both relative risk and helmet protection qualities, together with the freedom to choose, then I'll be happy. If bike helmets are mandated then I am certain that it will put some people off the idea of getting a bike.
Jeremy
I threw it back and said no thanks. 
