Originally Posted by
waterlaz
I believe short people usually have proportionally smaller feet. Therefore, to maintain the Knee Over Pedal Spindle principle you would need the same seat tube angle. I just imagine everything to be shorter (limbs, tubes, cranks ...) with the same angles.
I thought that it would be the same myself initially but it just doesn't seem to work out. I believe that its to do with saddle placement but I haven't sat down and drawn it all. I think the issue is saddle setback and the desirability of maintaining a reasonably constant saddle setback through different frame sizes. Since the nose of the saddle is in front of the post, and most saddles are of similar size then the seat tube angle needs to be relaxed to maintain the saddle setback distance over a shorter distance. An example would be that on very small frames even with say a 73 degree seat tube angle the nose of the saddle ends up in front of the BB. Crazy. 75 and 76 degree seat tube angles on small frames puts the nose of the saddle way in front of the BB.
That's what I think is going on anyway.
Anthony