I started wearing one a few years ago under my wife's insistance. "You go too damn fast. It scares me.", was her mantra. So I tried on a bunch and settled on a surprisingly light and comfortable Giro Nine.9. I actually don't notice it all when riding, unless it's warm and I get hot. Aside from the melon protection, it provides a couple nice advantages over hats. One, it's warmer. Next, it stays it place and doesn't shift around like hats. And last, I can lift my goggles up in the lift line and since they're on plastic and not a pervious, sweaty hat, they don't fog up.