Originally Posted by
Branko D
What - no. Given the choice, I'm going for pressfit.
The difference between a poorly done PF and an equally poorly done threaded BB on a carbon fiber bike is that the first will creak, the second won't. Both will eat bearings prematurely and waste more power than frame flex possibly could. Adding weight by gluing alloy inserts just so the manufacturer can mask their poor quality control on a multi thousand dollar frame - I'll pass.
This would be the right answer if the manufacturers of multi-thousand-dollar frames could be relied upon to meet the tolerances required to make a low-power, low-rpm press-fit bearing set work reliably.
They have proven over and over again that they cannot.
Despite the fact that every other industry has been using press-fit cartridge bearings for decades, in applications with orders-of-magnitude greater force and speed inputs, the bicycle industry can't make frames that will properly align a pair of bearings to cope with loads of less than one horsepower at 120 rpm without screwing things up. So the only way to get a BB / frame interface that doesn't suck is make the interface adjustable.
--Shannon