Watch out for camo-clad humans with guns during hunting season.
Start at the parking lot for the Alpine Tunnel Trail, and head up FS 295 towards Hancock Lakes. From the parking lot to the lakes is a fairly rough, loose 4x4 road. Around the lakes, it switches to singletrack and flattens out to cross the headwaters area before getting to a steep (20-30% grade) rocky hike-a-bike up to Chalk Creek Pass.
Go over the pass, and then descend on high alpine technical singletrack until getting to a parking area. Beware the conservationists with guns during hunting season.
Continue down FS 230, and prepare to get fast and loose.
If you want more, at a campground shortly before crossing Columbus Gulch, there's a singletrack trail that climbs up to Ross Lake Reservoir/Boss Lady Reservoir. The views there are nice, and then the subsequent ripping down the Syncline Hill 4x4 road is fantastic.