Maybe it depends what you see as "littering" - when I'm talking the city center here, without bike racks, people 99% line them up against the walls of the houses, or lock them on to streets signs, which are usually ~30cm from the curb next to the cars. I honestly can't remember when an actual non-rental, personal bike was in my way, so does not seem to be problem here, at all. If you define "they're all standing there", well, ok :P