East of Gunnison and Sargents, the 10 mile Agate Creek Trail (#484) winds through the Agate Creek drainage and eventually climbing up to the Continental Divide. Down along Agate Creek, the trail rolls through various meadows and dense pine forests. There are over 20 creek crossings ranging from a couple feet wide to 15 feet across, and since they are snow fed, they can be quite challenging during run-off.
To reach the lower/western trailhead from Gunnison, head east on US50. About 2 miles east of the very small townsite of Sargents, there is a small, unsigned dirt right on the south side of the road enter a small pine/aspen forest. This is the site of the old NFS Agate Campground. If you follow the access road, all the way in about 0.4 miles, you will reach a signed trailhead for Agate Creek Trail.
To reach the upper/eastern trailhead from Gunnison, head east on US50 to the top of Monarch Pass. You can park in the large parking area. To reach the trail, you will need to head south on the rolling Monarch Crest (Continental Divide) Trail for 8 miles.
The upper/eastern trail starts at about 11,800 feet. The lower/western trail ends at about 9,000 feet. Starting from the east, the trail descends from the Continental Divide about 1,500 feet over the first 2 miles, which are very rocky and loose. Then, it descends along the meadows of Agate Creek another 1,300 feet over the next 8 miles, which has some rocky sections.
Most mountain bikers drop a car at NFS Agate Campground and then shuttle up to Monarch Pass. By combining the 8 miles of Monarch Crest Trail with the 10 miles of Agate Creek, you will get an 18 mile route.
Overall, Agate Creek Trail is the 110th most popular mountain bike trail of all 175 mountain biking rides in Colorado.