I did not link directly to the study discussed in this article because it is only available as a PDF and over an insecure connection, but if you would like to skip to the source, it is here: <a href="http://elvumgar.fea.st/papers/Bike_Sharing_accepted.pdf" rel="nofollow">http://elvumgar.fea.st/papers/Bike_Sharing_accepted.pdf</a>