smashndash

It seems that you have a pretty nuanced grasp of the situation. Pressfit vs threaded is not what determines the quality of a bottom bracket. Just like how frame material doesn't determine the quality of a bike.

The optimal race bike would use pressfit. Either BB86 for shimano or BB386 for DUB/30mm. It's lighter, stiffer and theoretically allows for better alignment. There is no doubt about that. The only ? is how you would achieve the tolerances required for optimal performance on a carbon frame. With threaded, there is a floor on how bad the frame can be because you have to put in metal inserts and tap them. The tap won't fit if the hole is 1mm undersized. Plus you can safely machine metal to pretty precise tolerances.

I'll go as far as to say that BSA is a suboptimal solution for the modern race bike. There are 3 reasons for this.

1) BSA is not accommodating of 30mm spindles. BSA 30 bottom brackets use less material than BSA (24) to be able to slip a 30mm spindle through. This leads to less stiffness.

2) threaded adds weight. PF has less redundant material in the bottom bracket area. I think I've seen people claim a delta of about 100g.

3) outboard bearings are generally not a great idea. Yes, pulling the bearings outboard on a BSA shell from square taper to a 24 or even 30mm spindle allows for a lighter, stiffer overall setup. But you're not going to match the stiffness to weight ratio of an inboard T47 setup like what Trek uses. And definitely not the stiffness to weight ratio of something like BB386EVO.

That being said... these are all EXTREMELY marginal issues compared to the plague that is poor manufacturing. You'd be hard pressed to notice any of these issues on a perfectly manufactured BSA 30 bike vs a BB386EVO bike.

Overall... we should be pushing manufacturers to adhere to tight tolerances and should hold them accountable when they sell multi-thousand dollar frames that are out of whack. The specific standard they use is far less relevant than most people believe.