A difficult ride because of its length but not technically challenging.
The Glenn Spring Loop is one of several popular mountain bike rides in Big Bend National Park. The entire 35 mile loop is 100% dual track. While it is not technically challenging the ride is long. There are a couple of climbs that climb about 600'. The scenery is spectacular in this area.
How to get there:
From Fort Stockton head to Big Bend National Park via IH-10 and Hwy 385. Check in at the ranger station at Panther Junction and pay your $10 park entrance fee.
This trail loops around Talley Mountain via East River Road, South River Road, Glenn Spring Road, and Black Gap Road. The latter is not maintained and presents a few technical problems. It is also the most beautiful part of the ride. The Rio Grand River at Solis Landing, the Glenn Spring oasis, and the ruined Mariscal Mines are something you have to stop and see.
Bring extra water to this area as it is a long hot ride.