Citi Bike is New York City's bike share system. Columbia has no affiliation with Citi Bike and does not offer a discount on memberships, but its availability around Columbia's campuses makes it a good choice for getting to your destination quickly.
Citi Bike offers short term memberships which are ideal for visitors, or annual memberships for frequent users. Depending where you live, you might benefit from combining Citi Bike with your subway commute. You'll get more exercise and may even achieve a more enjoyable commute. Citi Bike also has pedal-assist electric bicycles throughout the network.