Houston wouldn't be my first choice for good riding nearby, but there are some options. The Sam Houston National Forest around New Waverly has some decent trails, mostly flat and sandy through the trees, with lots of roots. It's best when damp. There are some places to ride in Louisiana and around Austin, but the best stuff is a bit of a long drive away. Brock Creek near Jerusalem, Arkansas, is good, and there is a lot of great riding north of Dallas -- Red River (a.k.a. Muenster), Cross Bar in Davis, Okla., and the Kiamichi Mountains around Talihina, Okla.