Fairly smooth ride with occasional fun on blacktop, dirt road, single trails, and even through a tunnel under Rinaldi. Some nice steep sections, too. The full route takes you from the bottom of this trail, goes 3 miles to the top, then turns around and and comes back down for a good downhill leg. Should take about an hour if you're good, 1.5 hours if you're me.
How to get there:
Start near the maintenance yard just north of Devonshire and Tunney and follow the Mission Trail all the way up Limekiln Canyon to Sesnon.
The tunnel under Rinaldi is passable almost all year. The rocks and pools shift after a rain.