I just saw your post an hour after re-reading about bike fit by Lennard Zinn, a custom bike builder. He has a fine book entitled "Zinn And The Art of Road Bike Maintenence". The book has a good section on bike fitting. His website, https://zinncycles.com/, also has a section on bike fitting. I've not gone through the calculation on the web site but the bike book fitting advise is spot on for me.. Good luck.