There's a saying that goes:"logic is a way of going wrong with confidence".


Fit calculators and the various systems will work for many, and provide a good starting point for the rest.


But remember that your body has the power to veto any chart or equation based bike fit.


The trick for a new rider is to know what'll go away with increased experience/fitness, and what'll stay wrong.


I've got restricted flexibility in my lower back.
It's not immediately visible, as I'm over-flexible higher up.


But for extended rides, I can't use bikes that are fitted "by the book".


I need to use shorter stems, or bikes with shorter top tubes, to remain reasonably comfortable.