Several reasons, in descending order of importance:<p>a) I don&#x27;t have anywhere to store a bike in my apartment.  My work has a bike room, but it&#x27;s less convenient to use than the Citibike station right on the street.  My roommate used to keep her bike locked up on the street at our apartment, and it got stolen only a few months after she&#x27;d gotten it.<p>b) Even if I owned my own bike, I might still have Citibike anyway, because there are trips that I make (usually at night) where I use Citibike to go meet up with people somewhere, and then we continue traveling using other modes of transit, such as cab or subway.  Being able to leave a Citibike behind is really nice.<p>c) Maintenance.  I don&#x27;t have to worry about it at all beyond pressing a button when returning a Citibike that&#x27;s misbehaving.  There&#x27;s a non-trivial amount of maintenance involved in keeping a commuter bike running (especially one that&#x27;s ridden in rain and snow), and I just don&#x27;t have to worry about it at all.