if you don't spend all of your time in the front part of the drops, a straight bar will put you in about the same position as the tops of road bars. There isn't much of a fit issue. Make the seat fit your knees and legs; make the stem fit your upper body. Seems like bikes with shorter top tubes are older, and the trend has been to lengthen as they get newer - so the top tube will kind of depend on what age frame you buy.