Look for an open meadow just east of the saddle. Work your way downhill toward the bottom of the drainage. Just past a small vernal pool the track starts to take shape.
Stay on the east side. The trail starts as a deer path and gets better and better the father down you go. Roughly halfway down the canyon, riders will want to stay to the left for a longer ride on singletrack. The valley opens up on small farm patches and rolls across a creek bed several times. The crossings are easy to navigate, but there are short bumps up and out of the drainage.
Before long, the trail runs into the Berryessa-Knoxville Road.
I mark this intermediate/difficult for remoteness and route finding. The riding is all downhill and not difficult except for getting onto the trail at the very top.