There is also the existence of thicker / thinner cups that you can use with an axle with the races spaced for the other type of cups to compensate!
On Tue, Feb 16, 2010 at 7:19 AM, <firstname.lastname@example.org> wrote:
> Hi Richard. It's just as important. Left out of the discussion perhaps
> because TAs were almost never specced on Italian bikes and Stronglights only
> occasionally; perhaps. Given that the tread [[Q] is big enough that the left
> arm doesn't scrape the left stay, a 68mm axle in an Italian 70mm shell is
> going to bring the left arm 2mm closer to the frame centerline; not a huge
> deal. But the left cup is going to also thread 2mm more into the bb shell
> which might not leave enough exposed thread for the lockring. Cheers. Bily
> Ketchum; Chicago, IL; USA.
> ----- Original Message -----
> From: "r cielec" <email@example.com>
> To: "Classic Rendezvous" <firstname.lastname@example.org>
> Sent: Tuesday, February 16, 2010 8:42:27 AM GMT -06:00 US/Canada Central
> Subject: [CR] Current Discussions of Spindles - No mention of BB shell
> widths ?
> Ahoy !
> Yes, a poorly written subject line. Let's see if I can raise it better.
> I'm puzzled by my lack of knowledge to fully understand the discussion.
> In the recent spindle discussions, various spindle lengths were recommended
> based on taper standards (JIS, ISO, proprietary, etc...) and people's actual
> experience. There was no mention of bottom bracket shell widths (68 vs. 70)
> affecting spindle length.
> When I recall the often Campag spindle discussions, 68 vs. 70 is a
> significant specification in those discussions, and, Campag spindles are
> marked accordingly.
> Yet, in the current discussions of French focus on TA and Stronglight, the
> bb shell 68 vs 70 spec. did not come up. The discussion went directly to
> length without reference to bb shell width.
> I've come away with the notion that as long as one has the correctly
> threaded cups, all TA and Stronglight spindles can be used in both 68 and 70
> bb shells.
> OK - Why? Why isn't bb shell width as important to TA & Stonglight spindles
> as for Campag spindles ?
> Richard Cielec
> Chicago, Illinois; U.S.A.