Ride up Spaghetti Factory #116 (steep climb just after crossing a bridge) to Post Canyon Road #1400. Cross the road and follow the trail to Mitchell Ridge. There's a bit of a mess of trail intersections through this stretch. Just follow the most obvious trail as it gently climbs and begins curving northward.
Once you're heading due north, watch for a short connector trail on the left that will put you onto Mitchell Ridge. Follow Mitchell Ridge back to your starting point.