Sometimes just telling them will do it. The other day I was talking to my former PhD advisor who lives just down the street from where I do now, and he was horrified that I ride on that particular road, it's so narrow and curvy. Well, I don't routinely ride the curvy bit, just the part to get me to the main streets, but I have ridden the curvy bit, and I explained to him that although it is counterintuitive the thing to do is ride out in the middle of the lane--not the middle of the road--middle of the lane. Cars will see you, they will not hit you, even though yes, they go way too fast on that curve. They won't hit you. They just won't. But if you hug the edge, they won't see you, and will pass too close or even hit you.

He listened and just said "Really? I didn't know that. I wouldn't have thought so." But he believed me because, despite that I was his graduate student, I have been riding the streets of this city daily for a year.