I think around Central Texas, that is San Antonio and Austin, its the duration of the ride. Most cyclists live quite a far distance from work and doing more than a 40 minute ride becomes a chore. The other two things are of course lack of a place to clean up when you get to work, and having a place to secure your bicycle during work.
I know that's only three things but they are hard to overcome. Certainly its not because they don't want to ride...
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