Originally Posted by
Brian Ratliff
Think about it. Yes, you probably want the three contact points to be fixed relative to each other; however, there is no reason why you can't rotate the whole constellation around the bottom bracket to get a different position. There are plenty of riders who fit their saddles further back and their bars slightly higher and closer to create more power for climbing. Plenty of riders who have a bike with a longer, lower, more saddle forward position for flat races and sprints. Most time trialists and triathletes move their bars down and away to accommodate the much steeper seat tubes of modern time trial bikes.
Fit is all about getting the constellation of contact points right; position relative to the ground is a different story all together.
Sure, but setback determines the balance of your body on the bike relative to the force you're outputting into the pedals. If I set mine up with too little or too less, I get lesser or greater amounts of my weight on the seat and my hands, shifted from my feet. Even disregarding comfort issues, if you are not balanced on the bike, you can't transition properly - you have to shift your weight to stand for a climb, or a sprint, and then shift it again to sit back down. Impossible? Of course not, but isn't the point of fit to optimize your position on the bike?
Of course if you don't have to transition, this becomes a far murkier discussion - hence your very valid examples of TTs and flat races.