Fox Creek Loop is a singletrack loop on the Sawtooth National Forest about six miles north of Ketchum, on the west side of the Big Wood River. The Forest Service signs it as Trail 149 and rates it more difficult. It is one of the most popular intermediate rides in the north end of the valley because it packs a steady climb, a fast descent through aspen and a flat finish along the river into a ride of an hour or two.

To get there, drive north from Ketchum on Highway 75 for about 6.25 miles and turn left onto Fox Creek Road, Forest Road 020. Cross the river and follow the road a short way to the trailhead, which has parking, a vault toilet, a picnic site and a map display. There is no water and no fee. You can also start from the Lake Creek trailhead about four miles north of town, or ride out from Ketchum on the bike path through Hulen Meadows and pick up the loop by the river. The trailhead sits in the river bottom and can flood in a big runoff year. In June 2023 the Blaine County Recreation District reported high water there, and trail crews later repaired flood damage on the Chocolate Gulch trail right at the trailhead.

Published distances run from about 5.6 to 6.8 miles depending on the starting point. MTB Project measures the loop at 6.3 miles with roughly 740 feet of climbing and a high point near 6,640 feet. The Forest Service Trails Around Town brochure lists Fox Creek at 6.8 miles. The climb is long and steady rather than steep, and there is one small creek crossing.

Bikes ride the loop one way, counter-clockwise, and the Forest Service map marks it as a multi-use trail with bikes one way only. That puts the climb first, up the Fox Creek drainage through timber burned in the 2007 Castle Rock Fire. That fire started west of Ketchum on August 16, 2007 and grew to about 48,520 acres, and wind-blown embers started a large spot fire in the Fox Creek drainage. The upper loop is still open and sunny, with standing snags and young trees. Past the high point the trail drops through aspen on a fast, flowing descent, then turns south along the Big Wood River through cottonwoods back to the trailhead. Hikers can walk it in either direction, but going clockwise means meeting downhill bike traffic head on.

Chocolate Gulch Trail 312 leaves from the same trailhead and is the usual add-on. The Forest Service lists a Chocolate Gulch loop using Trails 312 and 149 at 4.9 miles, and Visit Sun Valley puts the Chocolate Gulch extension at about 3.8 miles and 615 feet of extra climbing, with views of the Boulder Mountains from the ridge between the two drainages. The North Fork loop on Trails 312, 149 and 303 is a quieter 2.5-mile option. For a longer day, the Oregon-Fox Connector, Trail 311, links to Oregon Gulch for an 11.6-mile loop.

The loop sits low and close to the river, so it melts out earlier than most trails around Ketchum, though spring can bring mud and high water near the bridge. Wildflowers come in early summer, and in September and early October the aspens on the descent turn gold, which is why local guides list Fox Creek among the best fall rides in the area. Elk and deer are common.

The trail is open to hikers, runners, mountain bikers and horses. It is closed to motor vehicles, including e-bikes. Dogs must be leashed within 200 feet of the trailhead, and owners should pick up after them. Bikers yield to hikers and horses, and when you meet horses, stop and step to the downhill side. Bands of sheep with guard dogs graze the Lake Creek area in summer, so keep dogs close and give the herd plenty of room.

Lake Creek and Oregon Gulch are the closest neighboring trail systems, and Adams Gulch is about three miles south toward town.