Houston has the most park space of the 10 largest US cities, with a wide range of other green spaces accessible to cyclists, many described in The Book.
Buffalo Bayou Park is a stunning $58 million recreational redevelopment of Buffalo Bayou between Shepherd and downtown, and eventually to be extended far to the east. The work is far along and the park is well on the way to becoming one of the best urban recreational spaces in the country, with excellent hiking, jogging and bike paths, art works, entertainment and eating venues, rentals for bicycles and kayaks, world class skate park and dog park, a bat observation site, and much more. For a complete overview and opportunities to volunteer, see their website.
This section of the Bayou has a rich history, partly covered in section 5 above on this page, and covered comprehensively in "Buffalo Bayou: An echo of Houston's wilderness beginnings". Many of the points of interest described in this book appear on this Buffalo Bayou cycling sightseeing route map.