Enumclaw, UT
Pedal or drive out the Behind the Rocks Road from Hwy 191 to reach Prostitute Butte, AKA Lone Rock. You can ride the loop in either direction: CCW as mapped will have you descending beautiful slickrock terraces under the steep NW side of the formation, but the slabs are just as fun to ride up if you prefer.
The SE side of the loop is sandy, so pick a day after recent rains or come in the winter for the firmest riding conditions. Or, just tough it out and push a little if you have to--it's not like it's a long way.
Watch for Balcony Arch on the south side of the formation, and Picture Frame Arch on the north side. The views of the Fins and Hunter Canyon are stunning from the north side of the Butte, while the south side offers great views of the La Sals. The area is particularly lovely at sunset.