This single track trail is part of the Sheltowee trace. This section is around 10 miles each way. the trail has technical sections, fast sections, and some easy flat sections with good scenery. The problem with the trail is that it isn't maintained very well. I find my self lifting my bike over, or around a lot of downed trees. Also the lack of maintenance has resulted in a lot of briers along the trail. the trail probably isn't something for a beginning rider due to some rough down hills and annoying trees across the trail. Over all I still enjoy the ride.
Take KY 89 north from McKee for 3 miles, turn right (east) on Forest Road 4, follow the signs for 3 miles. After reaching the camp gorund you will see where the USA trial goes up the hill. Ride up that trail about 200 yards and the single track trail will be on your right.
http://www.singletracks.com/item.php?c=1&i=4176