Originally Posted by
ColorChange
I can only speak for myself. I need a longer TT than normal geometries. You can get this in three ways, longer TT, seat back, longer stem or bars with more reach. If I size up with a larger frame to get the longer top tube, the bike feels too large and I have a hard time getting enough bar drop. If instead, I size down, the frame is lighter and stiffer, handling is quicker, I get better drop, but I have to slide the seat back and/or lengthen the stem.
Here is what mine looks like from an older shot.
Obviously the OP's set up really looks extreme (and probably wrong IMO), but in general, longer torso's can result in setback seat and or longer stem.
How the hell did you get the bike to stand by itself for that shot?
Back on topic. I got 2 words for you - compact geometry aka sloping top tube. It all comes down to being able to fit 4 different sizes of riders on 1 size frame. So that being said sizing up and down framewise shouldn't matter in bike performance that much, especially if you are in the middle between 2 sizes. Additionally when you size up down your OWN body measurements do not change so you need to adjust seatpost height,/stem etc accordingly. If you have to go to extremes (min insertion mark,140 or 70mm stem, etc.) the frame size is not for you (too big or too small).
-Carcinogent