Flume is a nice ride along St. Louis Creek. It's named after an old logging flume that runs parallel to the trail. Heading uphill, it's a fairly mellow climb. Downhill, it's moderate with some twists and turns, but you can really fly along this one with some nice flow.
In the direction mapped, it starts out with nice high alpine scenery, then narrows down to twisty singletrack through the woods, ending with a beautiful bench that serves as a nice snack spot overlooking the creek, and looking out to the mountains beyond.