Originally Posted by
Carbonfiberboy
Most builders at least used to decrease seat tube rake in the smaller sizes in order to decrease reach while avoiding foot strike. This isn't optimal either because it changes the rider's balance and causes more weight on hands.
It doesn't do anything because most people adjust for some desired relationship between saddle and pedals like KOPs or saddle aft enough to allow balancing in the drops position with hands off the bars. A steeper seat tube just means the saddle will be placed back farther on its rails which is more likely to call for an offset seat post.
That position will probably be farther forwards for a smaller rider with shorter femurs and less lengthy torso to counter balance, so a steeper seat tube will be more likely to keep the saddle close to the middle of its rails.