MountainBikeTX.com An amazing resource for trail riding in Texas as well as links to most other states. I highly recommend visiting this website because it is so well done and helpful.
BikeTexas.org The Texas Bicycle Coalition has a wealth of political, educational and practical riding resources such as trail guides. They deserve your support and interaction. (Advocacy)
BikeDFW.org Representing the Dallas Fort Worth region, Bike D/FW is the bicycle advocacy organization for that area. They can help find League Certified instructors for events and training. (Advocacy)
FWMBA.org Fort Worth Mountain Biking Association for racing, trail riding and building and more
DORBA.org Dallas Off Road Bicycling Association offer racing, trail guides, volunteer opportunities and more.