The trail can be ridden in either direction, but this description is for a clockwise loop:
Leaving the Bar-M Loop
at the Circle-O
's southern trailhead, ride 1/4 mile on dirt doubletrack to the berm bowl at the junction with the Rockin' A trail. This is where the real fun begins.
Head right (SE) from the berm bowl to follow the Rockin-A trail (it's well signed). The path is marked by a rust-colored line painted on the Entrada sandstone. Follow this line for nearly 2 miles as it winds through tight turns, over quick dips, and down short drops. This slickrock is slightly more difficult than the Circle-O
trail, but more fun. You'll come to the junction with Bar-M and can return to the trailhead on this trail, or continue south on the Bar-B Loop