Originally Posted by
RollCNY
Very well said, and again, I have never seen a drawing for a frame, so I may be picturing a positional tolerance that is unnecessary for a functioning assembly.
From personal experience, honing aluminum is a funny bird. I spent a great deal of time in a previous job working on honing aluminum manifolds (6061 and 7075) in an environment where everyone believed that honing was the best finishing method for size and position. I did some very detailed design of experiment to prove that it is all about L over D, amount of stock removal, and finish of the bore prior to the hone. It became fairly easy to mathematically determine which features may be at risk, and where positional movement could be expected.
But in general, I have no first hand experience with any of the press fit bores, largely because I like the easy of assembly and dis-assembly of threaded BB's. I defer to your practical expertise on the pro's and con's.
We speak the same language.
Good stuff and thanks for contributing your expertise.
With our background we also share the same disdain for BB30 because we see the tradeoffs.
I honestly admit to being slightly astounded that BB30 came into being. Not so much that a poor or challenged design is born...perhaps even with good intention...of stiffness and weight...but a design so flawed fundamentally and yet most top frame manufacturers have embraced it. Telling though isn't it?...that both Shimano and Campag never produced BB30 cranksets? They know.