Timed requests and parsing JSON in Python
While this is a good start, there are several things that should be noted.


  r = requests.get("http://citibikenyc.com/stations/json")


This is code snippet is network-based, and so errors may occur. You will want to handle these errors in some way, with a try-except block like so:

try:
    r = requests.get("http://citibikenyc.com/stations/json")
except ConnectionError:
    pass # handle the error
except TimeoutError:
    pass # handle the error


and so on, as per the requests documentation.

Additionally, do not sleep and do in the same function. These are two responsibilities and so should be separated as per the Single Responsibility Principle.

I would suggest adding the sleep(62) to the while True: block.

Also, there is no point to this:


  exit()


as it will never be executed. This leads me to my next point, you should probably do the file writing in Python instead of the command line, so you can open the file, append some data, and then close it to make sure it is safe between network errors and power outages.