This trail is gorgeous. Climbing then descending the east flank of Carr Peak, Cooper Loop earns huge views over the San Pedro Valley and deals thrilling downhill on the slopes of the Huachucas. The rewards come with substantial work, of course. The loop combines Perimeter Trail, Carr Canyon Road, Clark Spring Trail, John Cooper Trail, and Lower Miller Canyon Trail. Beginning from Miller Canyon Road along Perimeter Trail (riding the loop counterclockwise), it gets good right away with scenery and technical riding, but it will get even better.
After 3.6 miles on Perimeter Trail you'll reach Carr Canyon Road and face the only major climb of the ride. This is up the road for about 2 miles, and it is the relatively uninteresting part, with most views obscured by trees. A switchback with a clearing and a satisfying vista is your sign of a good time to come, as is the obvious trailhead sign for Clark Spring Trail. Hop on this singletrack and begin the downhill almost immediately.
The trail alternates between rocky and flowy sections it rolls along a ridgeline, dips in and out of washes, and switchbacks down the mountainside. This fun technical riding is made more difficult by the constant distraction of the scenery. You can see the whole valley far below and more mountains rising in all directions.
Just before the switchbacks begin on the downhill, a signed intersection marks the Miller Peak Wilderness, where bikes are not allowed. Take the hard left turn onto John Cooper Trail, where tight turns and small rock stairs await. Eventually you'll reach another intersection and a left turn onto Lower Miller Canyon Trail for a final short section of loose, rocky downhill before hitting Miller Canyon Road.
If you are ready to be done, you can ride the road down to the parking area, but the singletrack along the creek would be a shame to miss. Simply cross the road to find it. Flowy, fun, and shaded, this is one of the best parts of the whole ride. You'll bob and weave along the the creek and can even cross it on thrilling singletrack among the trees. Trails continue down into the neighborhood, so don't get too carried away and miss your car.
This is a fairly long and committing loop with lots of hazards that can damage your bike and you, so bring plenty of water, food, and repair supplies. No drinking water is available anywhere along the route, and most parts of it are exposed to sun.