The Croy Creek Trail System is a network of singletrack in the dry foothills a few miles west of Hailey. It is managed jointly by the Bureau of Land Management Shoshone Field Office and the Blaine County Recreation District, and it sees somewhere between 15,000 and 20,000 visits a season. The BLM lists six main trails totaling about 18.5 miles, ranging from beginner to advanced. Because the trails sit low on open sage slopes, they dry out early, and the usual season runs from early May into mid-November.

To reach the main trailhead, take Bullion Street west from Hailey, where it becomes Croy Creek Road. About 3.7 miles from town, past the Rotarun ski area, turn right at the Trailhead Road sign. There is a large gravel lot, a restroom and an information kiosk. The system can also be reached from the Rotarun area, from a smaller lot on Democrat Gulch Road for Lambs Gulch, and from a pullout on Bullion Gulch Road on the southwest side. Parking on Bullion Gulch Road is limited.

The main trails include Two Dog, the longest single trail in the system, which links Bullion Gulch with the Croy Creek side. Hidden Valley is a loop of about six miles on the far west end with an aspen grove and a rocky hillside. Bullion Connector runs about 2.7 miles between the Bullion Gulch drainage and the rest of the network. Centerline and Wilson Gulch are shorter connectors, Wilson Gulch being under a mile. Lambs Gulch is a loop of about four miles on an old jeep road north of Croy Creek. Punchline is a purpose-built flow trail, and the system has rollers, berms and tabletop jumps that make it a skills area for newer riders.

Motorcycles are allowed on part of the system. The BCRD and BLM identify the Bullion Connector and Hidden Valley trails as open to motorcycles. Two Dog, Bull Dog, Centerline, Wilson Gulch, Lambs Gulch and Nadya's Connector are non-motorized. Hikers, runners, equestrians and dogs use most of the network, but Punchline is for bikes only. Check the kiosk map at the trailhead before heading out, since designations can change.

The 2013 Beaver Creek Fire burned roughly half of the system, and erosion afterward damaged much of the tread. The BLM closed the trails, hired the International Mountain Bicycling Association to rebuild them, and brought in local volunteers for finish work. The trails reopened on July 1, 2015. The rebuilt network was designed mainly for beginner and intermediate riders, with a small advanced section. Croy Creek was later named one of the BLM Backyard to Backcountry mountain bike destinations, and the loop information for the area was put together by IMBA and the Shoshone BLM office.

Riders describe the surface as firm, gritty dirt with a lot of curves, and the riding is mostly intermediate cross-country with moderate climbs. A popular ride starts on Bullion Gulch Road and links Bull Dog, Two Dog and Bullion Connector into a loop. There is no fee to use the trails. Shade is scarce outside the aspen pockets on Hidden Valley, so bring water and plan summer rides for the morning or evening.