The Sunshine Trail AKA T35 is some of the most fun riding in San Miguel County. It leaves from highway 145, just south of Mountain Village and a few miles north of Ophir. There is limited parking right near the trailhead on the 145, but it's easy to park elsewhere along the road and just ride to the trailhead. Look For a small wooden sign on the south side of the road and the trail breaks down and right. The trail ends on 625 RD (Illium) and there are pullouts on either side of the road right at the end of the trail. This location is unmarked though, so if you set up a shuttle, go with someone who knows where it is.
This trail is just downright awesome. It's flowy narrow singletrack that rips through pine trees then aspen groves and ends in bermed dirt. T35 seems to run fast all the time but is at its best during monsoon season or after a rain when you can really open your bike up.
While this is not strictly a one-way trail, it is so fun and fast going down, that it probably should be.
The best ways to get home from this trail are to either ride 625 RD north to the Galloping Goose Trail, then all the way back to Telluride, or to set up a shuttle. This trail also links very well with Prospect
Trail into any number of Alta Lakes variations and finally T35. These linkups are perhaps the best trails in the whole Telluride area, but making the linkup work requires some trial and error in route finding. It is also important to note that there is a lot of private land in this area that needs to be respected in order to keep the Alta Lakes trails alive and well.