Northeast of Bozeman, the Grassy Mountain Loop (aka Bangtail Ridge Trail) is a route that switchbacks up Stone Creek and runs the shoulder of Bangtail Mountain. The route climbs 2000 feet of vertical over 15 miles.
To reach the mountain biking trailhead from Bozeman, follow Main east and turn left on Rouse Street towards Bridger Bowl for 11 miles. Turn right on Stone Creek Road to the gate. Park here.
Overall, Grassy Mountain Loop is the 32nd most popular mountain bike trail of all 32 mountain biking rides in Montana.