I recently introduced my girlfriend to mountain biking, and she's loved it but for one thing. Riders (usually experienced riders) who approach at high speeds, follow very close behind, and pass without asking or even calling out a warning have been a major problem for her, and in a couple instances causing her to go into the bushes. I realize those behaviors are pretty normal when you're riding with other experienced bikers but I don't think most people realize how it affects people who are new to the sport. I've been riding behind her to physically block people from getting too close but that can only do so much, especially on 2-way trails. My question is, what can we do as individuals or as a community to help new people be as comfortable as possible on the trails, and not let experienced riders be seen as a threat by new riders, so we can all enjoy this sport?