This is a relatively easy singletrack trail that follows the west rim of the gorge, offering some beautiful views of the gorge bridge. In the first mile there are some fairly technical--but short--sections. The rest of the trail has a few rocky sections where it crosses one of the many washes that lead to the gorge. It can get windy and hot on the trail, so an early start is recommended by the folks at Gearing Up bike shop in downtown Taos. They are also an excellent source of information, and have maps of most of the MTB trails in the area. IIRC, they cost less than $5, and include notes on the back from local riders.
Take US 64 west from Taos approximately 8 miles to the Rio Grande River Gorge. Cross the Gorge Bridge and enter the rest area on the south side of the highway. The trailhead is very easy to find, near the restroom building.
http://www.singletracks.com/item.php?c=1&i=4207