I passed one of these up near Dalston yesterday. I immediately fell in love with it's peculiar one-size-fits-all-and-blow-me-if-tiny-wheels-aren't-cool. As with almost everything else that's a bit strange, the mini-velo is the latest cycling craze in Japan.
The small wheels work well on city streets. Easy to get moving, turns on a dime (or a 1pence/euro piece) solid as hell.