Not Exactly in Utah
The Rainbow Rim trail lies on the northern edge of the Grand Canyon at an average altitude of 7700 feet. 18 miles in length, it links five viewpoints on the edge of the canyon. The riding is easier-intermediate in biking-skills requirement. Most climbs are mellow and followed by plenty of flat riding. You can ride a piece of it, or all of it.
I'm nominating this trail for "honorary Utah status" because Utah riders actually live closest to this trail. Cut off in the "Arizona Strip," it's a long way from Arizona's population centers. And because I didn't find a source of comprehensive information about this trail, we'll stick it here among southern Utah's rides. You're welcome.
Grand Canyon. AZ