There are several chainstays available for the S40, V20, and Q45.
16.5, 17.5, 19.5, 21.5, 23.5
Not all are always available heads up - we actually have a 95% fit rate for most riders which is awesome with a single frame size. The bigger issue is the one size fits all seat that of course adds a layer of fit complexity even above and beyond the chainstay. Stay tuned, however, as we are working on that as we are always working on everything
Longer is not always “better” depending on the bike even for taller riders. There are many issues in a fit other than just raw BB height.
Lots of moving parts and complicated adjustability in a single bike sounds like a great engineering solution, but only ends up in a highly adjustable mess that results in a floppy janky heavy bike that costs a fortune to manufacture. Simple is always better and swapping simple parts for fit makes more sense for us.
The bigger issue with multiple frame sizes is logistic - we have to manufacture X number of everything and less numbers = more expensive. Upright bike companies do not have the same market number constraints as recumbent companies.