To begin, head south on the Little Missouri Trail. In spots the trail is a little exposed with the creek bubbling below, and the trail surface varies from smooth to pretty technical. Although the trail is mostly downhill except for a steep 300 foot climb, there are numerous BIG creek crossings. Bring extra socks and be prepared.
Soon you'll turn right onto the Viles Branch Equestrian Trail. The trail here is loose rocks over hardpack, but no real technical challenge presents itself. It climbs steadily in preparation for the push up Fodderstack Mountain. It may seem hard; however, its nothing compared to the next portion.
Turn right onto Athens Big Fork trail. It'll be extremely steep and hard but doable. Then you'll start your ride along creek beds and over eight mountains. This is the part of the loop that separates the boys from the men, so mentally prepare yourself. If you're looking for a break, you can explore a cave 35 feet downhill from the trail on the south side of Brushy Mountain and a rock outcropping 150 feet from Brushy Mountain's summit. Overall, the beauty of the mountains will come out on this portion. The lively flora and fauna and the formidable terrain will complement each other perfectly. Try to avoid this portion in Summer, though. It'll be extremely strenuous with the heat.
To finish the loop off, turn right onto the first portion of the Little Missouri Trail. It's a very enjoyable downhill section, and it will give your legs time to rest before the long car ride out of the mountains.
Remember to avoid the trail after a heavy rain. The already high creek crossings will swell to impassable levels, and it's better to wait a couple of days than get swept away.