Originally Posted by
wphamilton
Because the center of gravity relative to the bottom bracket isn't as critical a consideration as people seem to believe. In my humble opinion.
In a way you've pointed out a flaw in the whole "crouch balance hands-off" test. Weight on the saddle changes the whole force vector picture, and hence the distribution of weight between the saddle and handlebars. A more forward lean from the saddle moves weight towards the hands, and that can happen moving either the hands forward or the butt back.
TT bikes have forward saddle positions because (1) TT riders support themselves on elbow pads, making hand pressure/fatigue a non issue, (2) TT riders want to hold a very low position (back flat or nearly so) for an hour or longer, (3) they can thus optimize the saddle position for hip angle.
Body CG relative to bottom bracket (the feet, basically) matters because, on a conventional bicycle, one of the rider's supports is weak and prone to fatigue (the arms and hands). So you want to reduce the weight on that support.
If all of the rider's supports are strong and non-fatiguing, then it doesn't matter much where the rider's CG is, relative to the bottom bracket. Recumbents are an example. To a much lesser degree, TT bikes are as well.