The main 12 mile loop is long and covers the gambit of uphill and downhill. It gets real sandy (and we do mean REAL SANDY) in the summer (June-Sept.) if its been dry. Also, you're going to cross the riverbed in the bottom of the canyon several times so you can get wet if it's been raining. (Also, the river bottoms are REAL SANDY whether they are wet or dry.)
The best parts of the trail are the descents into the bottom of the canyon and all the fast singletrack. The two climbs that take you back to the pavement and parking lots are murderous. (In fact only a few expert level racers have ever made both climbs.)
The trail is not exceptionally technical but it is long, rocky, loose and bumpy. (and VERY SANDY) This translates into a really fast ride and you can really get some speed built up when conditions are right.
Finally, there are also some other trails found in the Caprock Canyon state park. These include a rails to trails ride that will take you through an old railroad tunnel. If you ask at the main gate the Rangers will tell you where to go.
How to get there:
Quitaque Texas is located in the panhandle of Texas and is basically in the middle of nowhere. Luckily this means that the trails are generally unused and free of traffic.
The park is 3.5 miles north of State Highway 86 in Quitaque on FM 1065.
A local bike club from Quitaque holds an annual race in the park and does a great job.