I live within 2-5 miles of three different trail systems, all of which have singletrack. One is a National Recreation Area with a huge network of trails. So I don't drive to ride very often. I think it will be hard for me to ever live anywhere where I can't ride to at least some decent mountain biking. I would do less if I had to drive an hour to get to trails, and that would make me unhappy. Or at least I would do a lot more road riding (yawn).