Sure, but when it gets narrow, i.e., around turns, you can tilt the bike more, so it occupies less horizontal space. I've been in a situation where I needed to carry a full-size bike 3F up on a regular basis and Brompton, or another folder, is quite a bit easier. As to the neighbors, you wait on the landings for them to pass and you do it in an exaggerated fashion, so they get impressed by your manners . You greet them as they pass.