For the second time out on my mountain bike, I tried some slickrock on the Circle O trail. Slickrock (especially the infamous Slickrock Trail) made Moab the center of the mountain biking universe. This naked sandstone earned its name from early settlers riding metal-shod horses. However, for mountain bikes the opposite is true -- the rock grips tires like sandpaper.
Circle O is a good introduction to slickrock riding -- the BLM classifies it as beginner/intermediate. Head up to the MOAB Brand Trail system, and start on Bar M or North 40. You'll quickly reach Circle O, which is a 3-mile ride designated by a rust-colored line. It doesn't have any major climbs or really technical spots, but it's full of dips and turns. The views of Arches National Park and the La Sal mountains are incredible.