Originally Posted by
sanmi
It's a great question. I currently ride an endurance and gravel bike that each have trail between 65-68mm. I like both bikes but am interested in trying something different.
Even if I end up learning I prefer more trail, I'm still a little hung up on the relative differences across the geometry table. For example between the 49 and 52 there is a 5mm difference in trail and a 2mm difference in wheelbase whereas between the 54 and 56 there is a 3mm difference in trail and a 13mm difference in wheelbase. Going to the 58mm trail doesn't change but the wheelbase is another 14mm longer.
It's hard to say whether or not you would notice a change in trail of 5 mm. Trail is quite sensitive, so you might well feel it in a back-to-back test. 2 mm difference in wheelbase would be insignificant to the handling, so at least you can rule that out as having any effect.
But in any case I would go with the frame size that fits you best and not worry too much about these relatively subtle differences in steering geometry.