Very technical trail. Climbs and slick rocks are tough. You'll probably crash. 18 miles total if both loops are done, but you must do at least the first to get to the second. Don't ride alone. Very beautiful.
Take OK HWY 10, either North from Gore, or South from Braggs, OK. Greenlead State Park is on the east side of the HWY. The trailhead is well marked.
http://www.singletracks.com/item.php?c=1&i=1117