ADDISON COUNTY — Flowing down lush green mountains in Addison County’s backyard lies a state-of-the-art mountain bike trail that’s just begging to be ridden. In the works for more than three years, this nine-mile loop around Silver Lake and the Moosalamoo National Recreation Area is the first of its kind in Vermont: a point-to-point loop that traverses a significant distance of the Green Mountain National Forest.