Maybe they are embarrassed to come out and say they had an accident without a helmet and it hurt their head a fair bit!
After all they could have reduced the "hurt" by errrrrr wearing a helmet
I've had more years cycling helmet-less than with a helmet. Yet I've never had any head injuries when I haven't been
wearing a helmet. There is something else that can happen when you have an accident. When you KNOW that you
are gonna fall off your bike, you try and fall with it and protect your head. I'd rather one of my arms gets injured than my
head. Are people taking this into account? I don't think they are. We know that our head is more prone to serious injury than if he hit some other part of our body such as chest, arms etc.