Which rather raises a question over your speed.
Cycle helmets (even the highest rated) are only assessed at an impact energy equivalent to 12 mph
The claim that a 1% decrease in the chances of injury is worthwhile, I wonder about what percentage decrease you would gain by limiting your speed to a value that the helmet is validated for?
I would suggests that it is greater than 1%
Of course you could also achieve a far greater than 1% decrease by wearing a motorcycle helmet that HAS been validated to function at 40 mph
Or is that 1% really unimportant after all?
Hmm...you raise some fair points. I guess the rationalisation is that there is a tradeoff between my enjoyment of cycling (of which going downhill faster than 12mph is a significant component) and the inherent risk in doing so.
The issue really in this case is whether wearing a helmet reduces my risk of serious injury when whizzing downhill by 0%, 1%, 99% or whatever. If it's 1% then your argument is quite reasonable but were that it was, let's say, 10% then I think the balance of the argument changes
Full motorcycle helmet up the Snake Pass on a warm day = 100% chance of heatstroke so I'll give that one a swerve if you don't mind.