FATMAP difficulty grade
This is one of the best medium-length training loops near the city––with smooth, firm trails and a lot of hills! The climbs and descents are mostly all steady, with nothing too steep, and there's a good mix of ups and downs to keep things interesting throughout the loop.
It follows Corrals Trail, Bob's Trail, and Highland Trail through a mix of hillsides, ridgelines, and canyons in the foothills. As mapped here, the loop begins from Corrals Trailhead on Bogus Basin Road.
Parking there is a bit awkward, only available on the road shoulder opposite the trail.
Alternate parking with more spaces is just up the road at Miller Gulch Trailhead.
You could even start the loop at an entirely different point, like from Bob's Trail trailhead on Hearthstone Drive, or from the 8th Street extension trailhead.
The variety of options is another plus for this loop.