Only twenty minutes or so from Rotorua City is the Western Okataina Walkway, open to bikes and maintained by bike riding groups.
The trailhead is on Millar Road, near Lake Okareka. Take the Okareka turnoff from Tarawera Road not far from Forest Hub 2, and turn left at the bottom of the hill. Follow Millar Road to find the trailhead on the left a few kilomteres along the road, after the surface changes to gravel.
A beautiful ride through native forest awaits you, with a couple of honest climbs on the way out, which reward you with flowing downhill on the way back.
You will reach a junction, turning left takes you to a summit overlook with a spectacular view and some fairly tech trail, following along takes you down to Lake Okataina - its very steep and a difficult climb back.