[Stoat]

Are these electric or electric-assist bikes? If not, why do the docking stations need solar power?

 

I'm guessing that electricity is required to operate the bicycle locking system and the automated rental / money acceptance system.

This could never have been forseen.  Blame the riders!   ;-)

[TChad]

I think you are right. Here's the website:

http://citibikenyc.com/

It looks like an electric-assist bike, but it's just a very basic three-speed.