BB Shells

[jpw]

Is there a shell and bb standard that overcomes the problem of the down and seat tube intersecting each other before reaching the surface of the shell, the double miter problem?

[Peter P.]

Most of the press-fit BB shells are oversized, increasing your odds.

But the other factor is seat tube and downtube diameters. If you're willing to adjust your desires with those tubes, you can get what you want.

And the obvious answer is, the old 28.6mm seat tube and 28.6mm downtube standard with a threaded BB shell.

[unterhausen]

what's the problem with double miters? Lugged shells don't get rid of the problem, but its effects are much reduced. But there really is no problem assuming a competent builder.

[Butch]

Paragon does a 2-1/16" diameter T47 shell in an 87.5 mm wide (for internal bearings) so that you can offset the bb miter, and if needed you can ovalize it if not having a miter in the down tube for the seat tube is a priority.

The most important thing to do is make sure there is at least a fusion weld all the way around the seat tube on the bb shell under the counter miter.