I spooked one in an arena beside one of our trails the other day...when I was walking. I'm generally pretty cautious when I see them and I'm riding on the trail, but I've never been able to figure out what to do when running the same direction they're going. They don't let me by, but running by them is frowned upon, so...? Usually I just decide I'm at the halfway point and turn around, but sometimes I need a longer run.