This became my favorite trail this summer, as it's a fun technical challenge with some great views, and is uncrowded but easy to get to. When I ride this solo or carpool, I ride up Rapid Creek Road, but if I'm riding with someone else who drove there, we shuttle up Rapid Creek Road to the Rapid Creek Trailhead.
From Rapid Creek Trailhead, proceed up the two-track for a bit less than a mile. As soon as the two-track crosses Rapid Creek, watch for a red gate accessing the start of the singletrack. Follow the singletrack across two more private dirt roads, and cross Cottonwood Creek. Here is where the fun begins!
From here, the trail will switch back and forth as it climbs toward the ridgetop and bobs part way back down the other side. Eventually, after winding along the mountainside for a exciting few miles, the trail descends to an abandoned coal mine at the top of a box canyon.
From here, follow another two-track south for a few miles till you drop into a steep box canyon with a washed out culvert. You'll have to carry your bike out of the bottom of the canyon and across a ruined fence to resume riding. After two short, steep grinds out of narrow canyons, you'll pop back out on the top of the rim and come to an intersection with another trail. Check out the rock formations ahead of you here, and you'll find numerous animal pictographs adorning the sandstone walls. Don't mess with them!
At this point, if you're still feeling spunky, take the south fork. It's an out-and-backup to the next rim up, and south a few miles to a great overlook on the valley. The rock formations here are a blast for rock hopping, with tons of overhang caves and lemon squeezers to play in.
If you're not feeling spunky or are short on time, take the west fork, and the downhill fun begins! For a mile or two, enjoy the winding, rock hopping descent, and get ready for the steep at the end. The trail ends after winding around a very dangerous aquaduct at a parking area about half a mile south of the start.