Ellieb wrote:StopHeadway wrote:"
Cycling is safe. That doesn't mean there isn't room for improvement.. Which might include wearing a helmet
Quoted for truth.
Not trying to be facetious. But I cannot help feel that the 'cycling is safe' bit of the argument is predicated on helmets not being effective. It isn't about the dangers of cycling
per se otherwise we wouldn't be trying to make cycling safer. I don't think you can say that: "I don't wear one because cycling isn't dangerous, but I will campaign for a 20mph speed limit" without bringing in the relative efficacy of the the safety measures you are talking about. If you believe that helmets reduce head injuries as much as a 20mph limit then why wouldn't you wear one?
Well, that's a good point. To be clear, I would summarise my position as follows:
- cycling (without any safety measures at all, i.e. a "ground state") presents an insignificant risk of serious injury or death relative to all causes of serious injury or death. That is, while you can certainly be injured or killed while cycling, taking up cycling doesn't increase your chances of poor health / death compared with not being a cyclist. In other words, it is intrinsically "safe" (which is not the same as saying risk-free, since no matter the activity, someone somewhere has died doing it - a cyclist dies every couple of days in the UK, but about 500 people die from sedentary diseases, etc).
- helmets as a specific intervention do not reduce serious injury or death when worn by cyclists as a whole. That is (whether they are 85% effective at preventing head injury or not) there is a second order effect or another confounding factor which means that when we get people to wear lids, there is no overall protective effect. I find it fascinating to speculate why (increased risk-taking by cyclists? Closer or more careless driving?) but as with gravity, it's not necessary to understand the mechanism to understand the implications. In Australia, for example, the number of head injuries after helmet legislation plummeted - unfortunately, so did the number of cyclists. In fact, the number of cyclists fell by proportionately more than the number of head injuries which means the *rate* of head injury once everybody was wearing a lid was actually higher (who would have thought, eh?)
- In contrast, there are interventions which are positive, and don't contradict either of the above two points. For example, the chance of being killed by a drunk driver is incredibly low. You'd have to live 240 lifetimes to have a 'break-even' chance of dying in any form of road crash, and only around a sixth of fatal accidents involve alcohol, so that's way up around 1,200 lifetimes. Compared with a 1/3 chance of dying of heart disease *this* lifetime, that's pretty tiny, huh? But of course, what if we could eliminate drink-driving at a stroke (say with an undefeatable breathalyser ignition system) we could remove 1/6th of road fatalities at a stroke. This is worth going for, without question - but it doesn't change anything that I wrote earlier in the paragraph about how small a risk it is.
20mph zones are similar. Your chances of being killed in a 30 zone are so small that a 20 zone makes little material difference (how many thousand lifetimes are you willing to wait?) but unlike bike helmets, it's a win-win intervention - it improves safety without a downside. There's also the non-KSI factors to build in. A 20 zone is often far more pleasant to use than a 40mph urban expressway, so it encourages people to cycle more and this in turn has a lot of seriously positive health outcomes for them and those around them.
Helmets, on the other hand, are a harder proposition. No matter how you consider their protective capabilities, because of the 20:1 rule (health benefit vs risk ratio for cycling) it only requires a 5% reduction in cycling to completely eliminate the advantages of helmets (even 100% effective ones).
And so on, and so on. Certainly it's a lot more complicated than "we hit someone over the head then took their helmet off and tried again, shazam! Helmets for the win!" which summarises a lot of much-quoted research.