Originally Posted by
iansmash
my girl rides a 54 and she's like 5'5-5'6
don't forget, girls have longer legs than guys that are the same height (generally)
... and, thus, shorter torsos. My wife is 4" shorter than me, but we can usually ride the same bikes with very different saddle positions.
At some point you will at least need to fake a measurement if not get a real one.