Short loop of singletrack. Winding trail with some roots and rock. Not much for hills, but there is steep, short climbing. Beginners can do most of it, I think. There are Creek crossings too. Well maintained. Do as many laps as you want.
Take Lake Hefner Parkway to West Hefner Rd in Oklahoma City. Go west on West Hefner Rd. From West Hefner Rd. and North Meridian Ave. intersection, go north on Meridian about 100 yards, turn west (left) into R.R. Murphy Park. Soon after the entrance is a parking area, and a marked trailhead.
http://www.singletracks.com/item.php?c=1&i=1114