I have no problem with people who don't wear helmets. It's up to them. I see some people carrying helmets on the bike path, and that makes sense to me, because the risks are lower without motor vehicles. I tell myself I could do that, but I can't bring myself to do it. On the other hand, I often take Citi Bike without a helmet, and I even ride in traffic. Sometimes it's deliberate, such as the times when I know I won't be riding back in the other direction and don't want to carry a helmet. And sometimes it's because I get on Citi Bike unexpectedly. But I generally wear a helmet whenever I ride. I don't take my helmet off on my regular commute because, well, you never know what might happen. I was in a very bad collision long ago, and my helmet saved my life, so I continue to bet that I'll have another, even though it's not likely. It definitely is nice to go helmetless on hot days, I will agree.