Previously I described data I'd come across on the saddle positions of various pro cyclists. I plotted those results, showing lateral position of the saddle versus saddle height, each relative to the bottom bracket center, as follows:
The fit corresponded to a 66.4 degree seat angle with an intercept 93.5 mm ahead of the bottom bracket. So if the saddle was aligned with the sitting position aligned with a zero-setback post, then a slack, forwardly displaced seat tube would do the best job of fitting this diverse set of positions.
It was pointed out to me on the WeightWeenies forum that such a bike had been sold. Here it is: the Aegis:
I can superpost the data on the bike. First, I need to flip the axes, then I need to convert saddle height to vertical position above the bottom bracket. Here's the result:
The match is remarable to the numbers I derived previously.
Evidently the bike didn't sell. The issue is that it isn't needed: you don't need a single bike that will fit a broad range of rider sizes with the same seatpost.