I have been riding daily a Holland style bike (upright posture) for quite a long time. I now ordered a new e-bike online, with a more conventional shape (so I don't have a good body feeling for how I would sit on it) and for the first time in my life, tried adjusting the bicycle fit myself.
The seat worked well enough. The trouble came with fitting the handlebars to get the right arm angle.
This is a picture from the bike's user manual. It agrees with several online sources that the arm-to-torso angle should be 90°. This is confirmed by info provided by a made-to-measure bike manufacturer, and an article based on an interview with a bike sport physician (both in German).
The problem with that: when I measured myself and used drawings and Pythagoras, I got to to the result that my top tube should be somewhere between 77.5 and 89 cm (depending on drawing realism and handlebar height). Sitting on the new bicycle visually confirms these results - it has a "top tube" distance of 60 cm, and I would easily need 15 to 20 cm more for a 90° angle.
Now, I was quite prepared for a scenario where the ordered bicycle turns out to not be a good fit, so I would have to send it back and go offline shopping. But the problem is, when I browse different bicycle brands online, even the large frames are well under 70 cm in length.
What is the problem? Is it that producers just don't create bicycles for people with my ape factor? Or did I make a mistake in my calculations? Or is that 90° angle a weird rule that nobody achieves in reality? And if it is indeed that I have too unusual proportions, what are my options?