There are plenty of places to ride here that are relatively flat. There are also some darned steep hills if you know where to look for them, but nothing really long like climbing in Colorado.
What you can do with 48x18 also depends on your fitness level. For many years I rode with 42 and 53 chainrings and a 13-19 straight block in the back. I did almost all of the big hills with that combination. These days I'm much older and don't ride as much so I need 13-21 or even 13-24, although on my normal routes I don't go above 42x19.
We have a good number of big bike shops in the metroplex that have regularly scheduled group rides of different speeds and distances. I find plenty of riding around Irving mostly by myself and I have routes up to about 40 miles staying in the city, and much longer if you break out of the city into the rural areas. 99% of the time I ride from my front door, I don't go somewhere in my car and then ride. (I live a few miles west of where that football stadium was blown up.)
Last edited by bjtesch; 12-29-12 at 12:31 AM.