People, for sure. I'm a pretty defensive rider and I have no qualms about pulling off the road if someone is coming up too close. I'm never in so much of a hurry that I can't stop if I feel it would be unsafe to do otherwise. So long as I keep a wary eye on my rear mirror, I don't feel too threatened by inattentive drivers.

Intentionally malicious people worry me the most. I feel too vulnerable on my bike and I react very poorly to outright hostility. I had some rednecks in a truck follow along behind me and call me all sorts of crude unmentionables once, and I was worried they'd stop or throw something at me. As soon as another car approached, they left, but for the rest of the day I'd cringe a bit every time someone drove past. Even someone shouting the more common "get off the road" affects me more than it should, when I have only my own thoughts for company. My confidence in stealth camping faltered for a while after I got caught by a cop, who proceeded to talk down to me, accuse me of vagrancy, and berate me for traveling in such a way, alone.

Of course, for every bad encounter there are a dozen good ones. Even in the case of the ******bag cop, he ended up calling his superior, who told him to go away and let me sleep. He did. After the incident with the truck, I found a free campground with hot showers and was invited to a wonderful dinner with a couple of RVers staying there.

As far as other possible dangers... I've encountered a few black bears, but never felt too threatened by them. I've never been chased by a dog who didn't lose interest when I got off my bike. I carry more water then I need and a heavy duty tarp to protect my tent from hail. When severe weather is expected, I camp somewhere where I can get to shelter if the tornado sirens go off. Cold weather always used to intimidate me, but I have better gear for it this year, so maybe I can strike that off my list. I've gotten sick a couple times on tour, and quickly learned not to ride when I can't get food down, and that I'm not really better until I'm hungry. Catching a longer lasting bug worries me a bit, I imagine that would be pretty miserable.

Here is something I read on a crazyguy journal, which worked well for the author. Any time a vehicle slowed down to harass him, he'd start reading off it's license plate number at the top of his lungs. Pulling out a cellphone or camera would probably have much the same effect.