To Paris, while the MacBook was having a new logic board fitted (for readers who complain my arguments don't follow).
I can report that the Vélib' scheme (vélos libres, free bikes) is flourishing. Look at all the Stations Vélib' in one central area (detail from free bike map of Paris) (click to enlarge):
Go to a station and this is what you'll find:
If you nicked one you might have a job passing it off as your own. If you stand and watch, this is the sort of transaction you'll see (minus putting your card in the meter, which I failed to catch on camera):
I don't know what a visitor has to do to get a card but it can be done.