The Thunder Mtn. bike trail is a wonderful scenic single track trail located in Red Canyon. The trailhead is just a short drive from Bryce Canyon. You’ll take in some beautiful views as your ride through the hoodoos, red rock, and pine forest. It’s not too long of a ride, but it does get a little technical near the end. You can make it a loop if you don’t have a shuttle or second car. Start at the bottom of the Red Canyon bike trail(which is paved), and at the top you’ll take a right on to the dirt road. From there the trail head is only located a short distance. It’s quite an adrenaline rush at the end as you navigate some short switchbacks, and then ride through several washbeds.
There are quite a few videos on youtube of people riding this trail. See one at http://www.youtube.com/watch?v=hq_m_XNyo0c