I'm 6'0"/250lb and on the long side of a 31.5" inseam. I went with a 2010 Soho-S in the 20"/51cm size. It seems to be a good fit for me. I just raised the seatpost to get the proper leg extension. The sloping top-tube toward the seatpost can be misleading. If I straddle the top-tube near the head-tube, my boys are right there on the tube. Needless to say, when I step off the pedals, I have ample clearance at the mid-point of the top-tube. I straddled the 22" before I pulled the trigger...and although it felt okay, it wasn't the best fit....it felt tall-ish. With the exception of my recently acquired Madison, I tend to ride the smallest bike I can fit on with respect to top-tube length so I'm not all bunched up like a circus bear on a bike. Since your inseam is 81 centimeter (or 31.889"), I hope this info is helpful to you. Just keep in mind that your torso length and how the rest of you fits on the bike after adjustments might also influence your decision. The Soho-S is a fun bike!