For traveling west to east (downhill):
The trailhead starts in Middle Thompson Park, at the end of Forest Route 300.4M
and is clearly signed. Start with smooth singletrack with occasional rock gardens. As you go further, it gets steeper and rockier, with occasional marshy sections. Ends at the Thompson Creek Road #306
For traveling east to west (uphill):
Middle Thompson Creek is a tough uphill ride climbing out of the Thompson Creek drainage. The first two miles in particular will challenge your climbing skills. If you aren't in top shape you'll likely be walking. The last three miles level out somewhat. The trail ends when it hits forest service roads at the top. These roads lead into the Four Mile Creek drainage, past Sunlight and into Glenwood Springs.
Best ridden as an out and back ride or you might think about including it in a shuttle ride: leave one vehicle in the Thompson Creek drainage and drive the other up into the Four Mile Creek drainage. Ride the forest service roads to the Middle Thompson Creek Trail and enjoy the downhill.