chasm54

Having been away from the thread for a while, and now having read your contributions, I'm afraid that your commonsense position doesn't make much sense, for the simple reason that you don't differentiate between different types of head injuries. You say, correctly, that if you bang your head on the pavement it will probably hurt less if you're wearing a helmet. You could have added that you may avoid some cuts and bruises too. But you seem to believe that this is what matters. It doesn't, much. The type of injury you ought to be worried about is injury to your brain, not your scalp. Helmets do very little to protect against such injury because the amount of deceleration they provide is small, and they may actually increase the extent to which your brain is bounced around inside your skull by increasing the rotational forces acting on your head. They may save your scalp, but not your brain - and I know which of those I value the most.

And by the way, I speak as one who has tried your experiment. I have fallen off and hit my head when unhelmeted. Moderately painful, a few contusions, but contusions aren't much of a problem.

Cycling is pretty safe. All the evidence I have looked at seems to suggest that in general, encouraging more people to wear helmets does not make it safer. And the funny thing about "common sense" is that when looked at carefully, it so often conflicts with the facts. You'd do better to question your assumptions in the light of the data, rather than the other way around.