Funny that someone just posted a TMC bike racks map because I've been working on something similar, for all of the reasons pneumophila stated--incomplete, outdated, and scattered data--so I started making my own map of all of Houston's bike racks! It also includes other bike-related amenities, such as repair shops, repair stands, and water fountains.
Especially in a city and state and country that neglects or even vilifies alternative transportation, the smallest barriers can be frustrating or even discouraging. I hope that this can serve as a useful resource for anyone trying to plan their bike commutes.
You can check it out [here](https://www.google.com/maps/d/u/0/viewer?mid=1zpGXNrvJji2