Not a destination ride, Fort Rock State Park to Hole in the Ground is a CCW doubletrack loop which can include a 300' hike down into the hole (which is in the ground).
The loop is flat enough to be ridden in either direction.
Most of the ride is on barely used BLM roads or doubletrack, a pleasant way to spend an afternoon if staying in the La Pine area.
Fort Rock State Park to Hole in the Ground Trail
Arnold Ice Cave Trail 3963, Blackrock Trail 3935, Charlton Lake Trail 19, Clover-Lemish Trail 18, Clover Meadow Trail 21, Coyote Loop Trail 3962, Crater Rim Trail 3957, Crescent to Windy Lake: Summit Lake Trail 46, Cultus: Deer Lake Trail 6, Deschutes River Trail 2.3, Edison-Lava Trail 31, Lily Lake Trail 19.3, Many Lakes Trail 15, Newberry Crater Trail 3958, Parallel Trail 3958.3, Peter Skene Ogden Trail 3956, Swamp Wells Trail 3961, Windy Lakes Trail 3850, Winopee Tie Trail 16.5
Bens Trail 50, COD Trail 71, Edison-Lava Trail 31, Elfin Magic Trail 45, Farewell Trail 26, Flagline Trail 41, Flagline Access Trail 40.1, Flagline Tie Trail 41.1, Funner, Grand Slam Trail 44, Kents Trail 43, KGB Trail 72, Mrazek Trail 32, MTB Trail 51, North Fork Trail 24.2, Phils Trail 42, Sector 16 Trail 27, Skyliners Trail 28, South Fork Trail 25, Sparks Lake Trail 4, Storm King Trail 48, Swampy Lake Trail 23, Swampy Loop Trail 23.2, Swampy-Dutchman Trail 40, Swede Ridge Trail 52, Tiddlywinks, Tumalo Creek Trail 25.1, Tumalo Ridge Trail 25.2, Voodoo Trail 46
Ranking consistently applied to all of the listed trails.