I've posted this before, but here it is again.

Top is from 1933 57cm seat tube, 59cm top tube, middle is from 1950s 58cm seat tube, I think 58cm top tube, bottom is 2009 size L.






This shows comparing the bikes with the seats in the same position. The bars are all relatively the same. BB moves forwards and backwards. Wheelbase is vastly different.






This has the BB in the same spot. Surprising how the 1950s and 2009 are pretty much the same, only a longer wheelbase on the 1950s.