No lock. I thought they might provide a way to lock the wheels at least. The whole thing is set up to move from kiosk (or station) to kiosk. There are quite a few stations otherwise it wouldn't work.

There's a sign saying they encourage helmet use. Based on what I've seen, I'm guessing a lot of the people that have checked out the bikes so far have done it on a whim. Requiring a helmet would definitely curtail that type of usage.

Checking out a bike is completely automated. These aren't manned stations so providing a helmet and/or lock would make it more difficult.

I have wondered if the bikes are fitted with some sort of homing device that would allow them to be recovered if they were "lost". There's a $250 charge made to your credit card as a deposit. You are later credited that amount back.