Whilst entering the temple of false gods I came across this on screen sizing tool from Canyon, who I believe are a recognised German brand. I have neither the knowledge nor the benchmark to offer a view as to its usefulness but its certainly worth a look. You might gather some transferable information for use when 'returning to the fold'
Here's the link:
https://www.canyon.com/_en/roadbikes/bike.html?b=3192
