@lerk @juliette I think this is still an evasion of the point. I'm saying that what validates using a helmet is that even if your chance of hitting your head is half as high as when when the kinetic energy when you do, is likely to be much higher.But i don't disagree that traffic ought to be optimized for cyclists and other "soft" travellers, rather than for motorists. Wearing a helmet doesn't have any bearing on the most dangerous risks of riding a bike.