there's something very seriously wrong with the planet we are living on.
Yes. Lots of things.
Back to helmets ....
My helmet definitely helps reduce the effect of scraping my head on canal bridges. the extra inch or so makes me do it more often though.
I have a strong suspicion it wouldn't be any help at all if I had a crash at my normal level ground riding speed of around 15 mph. I'm not however planning on testing this hypothesis if I can possibly avoid doing so!
It might be some help if I fall off my bike when stationary, or at a few miles per hour.
If a car/ van/ bus/ lorry hits me I don't expect my helmet to be of any use whatsoever, irrespective of my speed. I try very hard to stop this happening. The effort put into trying to avoid being in a collision is likely to protect me much more than any helmet.
My helmet helps keep my head warm in winter. This is by far its most useful function.
My helmet makes my head get too hot in summer. When it does I do what Cyclecraft tells me to do and take it off. I then feel much more comfortable, and don't believe I'm any more likely to suffer a serious injury than if I was still wearing it. Unless I'm riding along the canal.
Who invented the damned things in the first place? Their manufacturers of course. Ah - so who profits from making them compulsory or otherwise unavoidable then?