In Japan its very common to leave bikes unlocked. If they are locked, its often with the on-bike kind which lock the back wheel only, so it can be still picked up and walked away by lifting up the rear tyre. (The keys on these locks can only be removed when the bike is locked, and I have heard that in the case of theft possession of the key can be used as proof that the bike was locked when left, but I doubt it happens much). When I lived in Tokyo though, I locked my bike out of habit, but also because I liked to leave my bike anywhere convenient, but this is not allowed and the city council workers have the right to remove any bike not left in a designated parking spot. Happened to me once, and I had to go a big storage cage outside the city and prove ownership. Typically for Japan, this is considered very shameful, lol.

The weird thing though, given how rare bike theft is, was the one time I did a female friend a favour and went to collect her bike which had been left out on the street (too drunk to ride home) and I found it with her saddle missing! Odd for Tokyo I thought. It was many years later that this mystery was solved: http://www.rawstory.com/rs/2013/08/2...-bike-saddles/