Click on this pic to get the full effect. If this picture isn't evidence that mountain bikers need trails, there is no evidence. This is an advertisement from the International Mountain Bicycling Association.
I've been a mountain biker for 4 years now, and ride a full-suspension Giant VT1 modified. Now that I'm a pastor, and living in the flats of Northern Illinois, it's harder to find and ride trails. It's hard enough to just stay in shape! But I'm doing my best to keep up this passion of mine.