256 miles. Although, technically, the last two hours of that were after midnight and on the "next" day. That was a 400k randonneuring ride. I've done a couple of 300k rides (190 miles or so) and a 600k ride, which included 225 miles the first day and the rest on the following day. This was all on my Raleigh Sojourn.

My previous bike was a Worksman single-speed cruiser. I did several century rides and a 130-mile brevet on it.