Once you reach the West Cucamonga Truck Trail in the west, you can not continue onto the Sapphire Falls Trail as the area remains closed.
The climbing adventure begins off Archibald Avenue and travels through Demens Canyon for the first two miles to reach the great views at the top of Angalls Canyon. From there, it begins a zig-zagging fast descent through the winding fire road switchbacks.
Next, you'll come across a portal-like entrance over a small stream that takes you into a rocky singletrack climb and a singletrack escapade passing two gates and what seems to be Scooby Doo's missing Mystery Machine van crashed in the canyon (see photo).
Unless you've set up a shuttle, turn back the way you came and repeat going the opposite direction.