I have a friend who ran hurdles, and told me that running is leaning forward with legs going up and down. I saw a bike position video that explained the same thing relative to saddle and handle bar position. So I tried a bunch of bikes and came to appreciate the sloping top tube and long head tube for my desired riding position. This gave me the relative position I wanted (on and off the saddle). I ended buying a Specialized Roubaix 2015, the bike geometry gave me my desired position.

So with this said, bike geometry is relative to body measurements for fit. I tried several manufacturers, in two sizes per bike. I determined that larger frame felt good on saddle but too large off saddle. The opposite with the smaller frame size, but on the saddle, with a longer stem gave me better aero performance. I went with the smaller frame. Comparing all of the geometries, they all were within a cm or so (Stack, Reach, TT, and Seat Tube) Which is adjustable by stem or seat post for fit.

My body measurements and bike fit to maximize performance is always on my mind. So as you mentioned 5 hours on a bike required comfort. I can’t imagine 5 hour of sprinting. So comfort drove position, and position was addressed by bike geometry. That is to say, if I wanted pure performance, i.e., Time Trial, I’d have a different position hence a different geometry. Then given my body measurement I’d find a bike that fits. The 3:00 knee, for me is impossible for the type of bike I want and my long thighs and longer calves. I may be able to get it with 180 length cranks but I never tried. Also, peddle radius and cadence is important to performance but is also a complex matter I’ll set aside for this discussion.

Conclusion: Once I figured geometry (which I think is the bike type e.g., road, mountain, endurance, hybrid, touring, or cruiser etc.) fit became the goal. Once I was able to achieve fit, ride performance was compared. Lastly, unless you get a custom bike, off the shelf geometry is really a comparison once you have ridden the different brands and models for a given type. I found myself comparing different geometries for different bike types for position. Different geometries within a type for fit (given my body). Thanks for letting me share my experience. I hope it makes sense.