The other half of the story is more compelling. The hygienist, seeing his cycling attire and then grilling him over whether he had a helmet.

I'll admit that when I do wear a helmet, that type of situation is part of the reason. Sometimes the only reason. I just don't want to deal with conversations with safety nannies and don't want to return their rudeness. And also I've found that carrying a helmet excuses the attire, or at least explains it and heads off comments about that as well.

The takeaway is carry your helmet in with you.