Southwest of Sun Valley, the Greenhorn Gulch / Mahoney Creek loop is a 12.2 mile mountain biking route climbing 2,100 feet. The route combines the trail up Mahoney Creek (6.2 miles / 2,100 feet) and returns via the Greenhorn Creek Trail (6 miles / 2,100 feet). The route runs through beautiful pine and aspen forest with some sections of past wildfire damage. The wildflowers are amazing during mid-June.
On the descent, there is another excellent spur trail leading back to the trailhead parking heading up and over to Imperial Gulch.
To reach the mountain biking trailhead from Ketchum, head south on SR75 for 5.5 miles. Turn right heading west on Greenhorn Gulch Road for 3.5 miles to the trailhead parking area located at the end of the forest service road.
Overall, Mahoney - Greenhorn Gulch is the 27th most popular mountain bike trail of all 63 mountain biking rides in Idaho.