Originally Posted by
guadzilla
So since you are a math genius, quick - what is the fore-aft difference between a 72.5 degree STA and a 74 degree STA on a 82cm seatpost (BB to saddle top), which is longer than what most people will ride?
And what is the length of a typical saddle rail?
You do know that you can move the saddle back and forth to get the right pedaling position, right? And stems do come in more than one size, right? So given that the vast majority of people do not ride with their saddles slammed all the way on one end of the rails and with a 140mm stem on their bikes, what does that tell you?
But hey, stick to splitting theoretical hairs on the interwebz with your superior geometry skills.
What this tells me is that bikes have a lot of adjustability. The puzzling thing is why you think ETT is important.
If you want to get the "right" frame size... which means you have standard parts in "aesthetic" adjustment ranges... the most important aspect to look at is head tube length. This analogous to the old frame sizing method of looking at seat tube length when top tubes were horizontal.