I am generally a sports-tourer type of rider and recently finished building my first lugged steel frame. I am thinking about my second frame and I think I would like to build a frame that could take either 650b or 700c wheels; a good number of people who share my riding style rave about 650b, so I figured that it would be good to give it a try.
Anyway, what types of things should I consider when building a frame that will work with up to 700x32's and 650x38's? Or should I just design a 700c frame with short-ish brake reach (49mm, most likely) and an average amount of BB drop (75mm...on the low side, I know), and know that 650's will work with longer reach brakes? Would any geometry changes from 73 degrees parallel and 50mm or so of fork rake be advised?