Start off on a trail next to Keystone Ranch Rd for a few hundred feet, but then, due to logging operations, get back on that dirt road for a couple hundred yards until you see singletrack branch off to the left again. You are now on top of an aqueduct and you follow this for over a mile.
You snake through neighborhoods and open hillside, sometimes directly in the aqueduct (where it's not contained in pipe). Surprisingly fun!
After the neighborhood ends, leave the aqueduct and climb gently uphill through a massive logging operation. In summer 2013, there were MASSIVE piles of dead lodgepole pines waiting to be burned. Kind of sad, but due to the hills and big mountains in the distance, it's surprisingly scenic. And the trail flows very well, and is lots of fun.