Will a helmet prevent an accident? Maybe, but it's a stretch. I can hear better with a helmet on because it filters out wind noise, and protection from bugs and road debris can help, too. Still, it's a bit of a long shot to say that it actually prevents accidents. That said, there is no doubt that wearing a helmet makes surviving an accident without a serious head injury much more likely. I can't say that I've never ridden without one; however, I can say that it's been a very long time since I rode without one, and I make it my practice never to saddle up without a good one securely strapped to my noggin.