I'd recommend the contrary about the rack. With a rack, the Brompton rolls easily, especially across the smooth floors of the Penn Station. It even does OK on subway platforms. My wife is not keen on carrying her Brompton any more than possible, and we find that we can roll them along nearly all the time other than carrying them on the stairs. I suppose the upgraded wheels work fairly well on the Brompton without a rack, but I'd still put one one (actually, we have them on both of our bikes).