Originally Posted by
Psimet2001
Ahahaha.... Looks like there has been a lot of religious debate on this. I didn't bother to read it all but got most of the just.
BB30 has been touted initially with lots of "advantages"
It is in fact easier to machine. When you thread you have to first bore and then thread. In bb30 you just bore. It reduces the process and tooling and overall expense, but that isn't really the reason to do it. There are easier ways to reduce the cost in frame manufacturing without resorting to removing a threading step - one of the simplest steps and oldest machining processes.
Bb30 has become the bane of most mechanic's existence. It's easy to assemble and service with the right tools, but almost all of its incarnations have resulted in early bearing failure from poor sealing, or creaking between the pocket and bearing.
There are a lot of ways that have been developed to "deal" with these issues, but they overlook the fact that the threaded setup just works better. Sorry.
Pressing out bearings and replacing does wear on the bearing pocket. Pocket tolerances for bearings are actually. Fairly critical. The wear contributes to chronic pocket/bearing creaking. This is not the case with threaded connections.
True. Above is pretty obvious to engineers that look at the design of BB30 and contrast it to an external bearing threaded BB.
As I stated in previous threads, I believe that PF30 will supercede BB30 for some of the reasons you mentioned. But not PF30 in its present form. Praxis has come forward with a very solid aftermarket BB to be used with PF30. It maintains PF30 Delrin bushings in fact. But major difference. It is a collet sleeve that expands radially when threaded in place. This uniform expansion works nicely with a plastic bushing and hard carbon shell. But there's more. The reason why it is so effective is...it is a solid sleeve that is stabilized by both both sides of the BB..unlike current PF30 where bearings are independent...the true achilles heel of both BB/PF30 in contrast to threaded BB.
I foresee that BB30 will go away over time...in part because it offers very little economic advantage as you state compared to threaded BB and PF30 if done properly can be made rock solid and maintain the advantage of larger diameter crank spindle.