The Fremont National Recreation Trail is a long 130ish-mile trail that is all open to bikes but most of it is currently impassable from beetle kill, fires, and disuse. This segment is infrequently used but is cleared except for the occasional blow-down. There are future plans to clear the entirety of the FNRT and incorporate it as part of the larger 650-mile Oregon Timber Trail.
If you've made the Forest Road, School House Road #020, climb to the top of Morgan Butte, you're in for great views and a backcountry treat as you roll along high meadows, and scream through soft beds of pine needles.
Nearer the bottom, you'll find a few sections with a little more pedaling than you'd like, but no real climbs to speak of as the trail winds down to the valley and road below.