A hot topic for sure and I guess the industry would say you need to get a professional bike sizing to get the best fit, or at least that's what I keep seeing in videos. I think it makes sense to get a bike sizing but what about having multiple bikes, never mind multiple bike types? I have a newer Cannondale bike, 56 cm that I feel fits me quite well and I can ride it for long distances with minimal issues, despite never having got a bike sizing. But then I jump on one of my older steel bikes and now I'm on a different bike geometry and so does that impact the comfort I should have?

Same thing when I ride my 90's mountain bike which is a different geometry and different sizing consideration than the road bikes.