Battles Not Worth Fighting

Tim Harford responds to a letter in the FT from a cyclist who has this (among other things) to say about the debate on helmets and cyclists' safety use:

In London, half of road deaths are pedestrians, just 6 per cent are cyclists. I cannot understand anyone involved in casualty treatment who insists cyclists should wear helmets, when they themselves do not wear a walking helmet.

Here is Harford's response:

Very interesting. The argument is not watertight, though, for a couple of reasons. One is the Peltzman effect: it could be that behelmeted cyclists take advantage of an increase in safety by taking more risks, such as cycling faster and running more red lights. If that was true (I am not aware of any research on the question) then helmets would not seem to make cyclists safer from the view of the statistician, but they would be giving cyclists the (privately) beneficial ability to get to their destinations more quickly.

Nor is it true that helmet use is justified only if cycling is more dangerous than walking or driving. That is not the question: the question is the marginal benefit of the helmet. If pedestrians don’t wear airbags, that is not because walking is safer than driving, but because airbags offer no benefits to pedestrians.

Interesting to note that half of London road deaths are of pedestrians and six per cent are of cyclists. Proves nothing by itself, but ten times as many “journey stages” in London were by foot as by cycle. (source: p6) That suggests, broadly, that the risks of a cycle journey are about the same as the risks of a pedestrian journey. Who knew?

I’ll keep wearing a helmet. I am

a) Risk averse and more importantly

b) Signalling to my wife that I pay attention to her opinion.

I would suggest that the two cyclists who read this blog pay special attention to reason "b."