This is an outrageously rocky trail running through the West Mancos River gorge.
Begin at Golconda and ride 0.6 miles up the road. Turn left onto singletrack and the fun begins. There are some smooth sections, but mostly it is unrelenting chunk. Cliff bands have funneled a steady supply of talus down into the gorge and the tread is correspondingly rocky.
This trail can be ridden uphill from Mancos Box Canyon to form a loop. This is quite a grind and requires extensive walking. A better option might be to ride down this trail, then climb gradually up Mancos Box Canyon from the east end.