I like a lot of the responses here. One of my techniques for discussions like this is to start with finding common ground. So if someone says it's dangerous out there, I say, "Yes, I know. Some people are just crazy. To ride a bike out there, you really have to know what you're doing." Bam, I've just implied that I know what I'm doing. If someone wants to hear what expertise I have and how I acquired it, I'm happy to discuss that. The fact is that skill has a huge bearing on how safe you are on a bike. It matters more than whether you wear a helmet, and that's why I'm not a helmet advocate. I wear a helmet, and a helmet once saved my life, but I don't talk about it, because I'm on the skill bandwagon instead. And please, let's not discuss the merits of helmets.