The Silverton area has become a mecca for the hydrocarbon crowd but there is some MTB singletrack available in the form of a Colorado Trail segment from Stony Pass eastward to West Pole Creek Trail
. Although this segment is short it's all above timberline and a serious alpine ride.
Getting to the trailhead can be a bit of a challenge. The furthest up that street vehicles can reach is the "Five way intersection": see "P" icon on map. From here you can drive a 4X4 or ride your bike: 4.4 miles, 2800 vertical feet. At least one company in Silverton will shuttle you for a fee that might leave you breathless.
Since I like riding singletrack not roads I tried another option. This area is typically busy with 4X4s, quads, side-by-sides and all manner of OHV power, so I hitchhiked.
Every full vehicle stopped to chat and within 20 minutes my bike and I were climbing the mountain in a 4X4. This is a great way to talk with folks you might otherwise not meet. One disadvantage is it might not get you an early start which is important for alpine riding.
The trailhead is about 1/2 mile down on the east side of the pass.
This is a serious trail. It's steep, narrow, loose, and off-camber in spots. The elevation never drops below 12200 feet. Start early, take plenty of liquid and calories, and be prepared for wind, rain, sleet, and hail.
The trail contours north along Canby Mountain. You'll rise to a saddle that overlooks Maggie Gulch to the north. From here the trail heads east, climbing steeply around 1.4 miles, passes small ponds, and then drops to West Pole Creek Trail
If you continue about 0.8 miles further east of the West Pole Creek trail junction, you can hit 13,000 feet.
Note that the segment of the CT immediately to the west of Windy Pass goes through wilderness, so all the through-riders have to go down to Silverton and up the highway to Molas Pass. The next section that mountain bikers can ride is Colorado Trail: Molas Pass to Engineer Mountain trail.