We have a couple of Road Nazis who insist on doing the local training ride on Saturdays (which is often quite the race pace hammerfest) sans helmet. I think they're insane. I wear bicycle and motorcycle helmets daily. The bicycle helmet is so light that I've ridden for an hour before I realized I accidentally left it home. Feels the same with the helmet on as it does when you're not wearing one at all, that's how light they are. With a motorcycle helmet, it's like you have a refrigerator on your head. But I don't ride my ST without my Nolan helmet either.

I only have one brain (such as it is) and I need it, even for BF.