Originally Posted by
d_dutchison
This one on frame design suggested that the main impetus behind the move to sloping top tubes is that one frame size can accommodate a much wider range of differently sized cyclists, so fewer sizes of any given model need to be produced. The ultimate purpose was to reduce production costs, which in the case of custom carbon-fiber would be several orders above astronomical - to the point of being impossible.
Has anybody confirmed that this is actually true? The reason why I question this line of reasoning is that, as far as I can see, modern frames with sloping top tubes are offered in the same range of sizes as older frames with traditional top tubes. If anything, modern production frames are offered in
more sizes than many vintage production frames, especially on the smaller side of the spectrum.