You might find some useful info from these two sites:
San Antonio Wheelmen
http://www.sawheelmen.com/
Austin Cycling Association
http://www.ccsi.com/~aca/
Austin has the most active cycling community and enough political influence to restrain anti-cycling forces. San Antonio is much larger but has a less active biking community...centered largely on the northern outskirts of the city, adjacent to the Texas Hill Country. If you don't need to be located in a large urban area, consider New Braunfels, Boerne, Canyon Lake, or Kerrville. These areas have an active cycling scene, and are located in the most beautiful areas of the Hill Country.