.40 miles and 35 miles
We visited the Forest Service office near Rapid City, SD, and got the Motor Vehicle Use Map, which shows all the trails in the Mystic and Northern Forest.
The first day we trailered to Nemo to the trail head and rode on nice real trails to Hwy 385, past the Sugar Shack (a great burger joint) to other trails and made a nice loop back. Some of the trail turns to a gravel road, but the hills were fun, the trees were at their peak.
The second and third trip we trailered to Piedmont, to the trailhead and choose trails to make a nice loop. There was a huge canyon with sandstone cliffs, ponderosa pine, aspen at their peak colors and a 40ft hole, where the ground had fallen 25 ft down and numerous caves.
Having the Avenza map on the phone was a help to make sure where we were at.