Velosiped126

My basement is a repository of cycling components, some mine and some left by cycling buddies who did not want to take the stuff with them when they retired to a warmer location or moved back to their home country after a stint in the U.S. So, in parting out during the pandemic, I have come upon a Campy Chorus sealed cartridge bottom bracket with a 102mm spindle that was not mine and is Italian 36mm x 24TPI, but has a shell width of 73mm.

Before unearthing this BB, I thought that Italian BBs have a shell width of only 70, while British BBs come either with a 68mm or a 73mm shell width. I have never encountered an Italian BB with a 73mm shell width, so I am confused. I perused Sheldon Brown's site, but he makes no mention of an oversized 73mm Italian BB. So I would most appreciate a consultation.

Am I measuring wrong? I would post a photo of the BB with calipers, but I am too new to post photos yet. As I ride vintage machines without sealed cartridges, am I stuck in an old school BB time warp? If I am measuring correctly, then is this for a mountain bike?

If someone much more knowledgeable than me would post an explanation and perhaps a photo, then I would greatly appreciate it. Thank you.

alcjphil

How do you measure shell width if the bottom bracket is not installed? This sounds like a Record/Chorus lever square taper bottom bracket. It would be fairly normal for the non drive side cup to protrude a couple of mm when installed in an Italian threaded frame

Velosiped126

Thanks for your reply. I am measuring the bottom bracket cartridge itself, not the bottom bracket shell of a frame. And yes, it is a Campy Chorus sealed cartridge bottom bracket cartridge, so I am trying to determine the specs of the component itself so I can specify which bottom bracket it would fit.

Litespud

I'm confused - how are you inferring the BB shell width (which is, after all, a measurement taken from the frame BB shell) from the uninstalled BB cartridge? What are you actually measuring (ie, from what point to what point) to come up with a value of 73mm? Certainly there are cartridge BBs intended for 73mm BB shells, but I don't know that any dimension of the cartridge itself is actually 73mm.
I could be wrong, but I would have thought that the cartridge was a standard BB-width-agnostic item, and that the BB shell compatibility, in terms of threading and width, was governed by the cups. I don't recall ever seeing any BB shell specs written on any Campag cartridge, other than "Left" and "Right".

JohnDThompson 

Shell width in general is a poor predictor of thread spec. BITD, Campagnolo also made Italian thread bottom brackets for 65mm shell width, many bike-boom era Japanese bikes have 70mm English thread shells, and of course any frame that started out with English or metric bottom bracket threads could have subsequently been converted to Italian thread if the original threads were somehow damaged. Many mountain bikes used 73mm shells, so although I've never encountered an Italian thread cartridge for a 73mm shell, it doesn't surprise that they exist.

Velosiped126

I am measuring the BB sealed cartridge itself, from thread end to thread end. Once I have ten posts (I am at five right now), I can post a photo of my calipers in action.

I inherited another Campy Record cartridge that is English, but measuring it as I do the Chorus cartridge, my calipers say the shell width is 68mm, which makes sense to me from what I know of old school English BB shells.

So, at least from my measurements, sealed BB cartridges are not shell width-agnostic, but are of a specific width.

With my vintage components, the BB cups have to match just the threads of the frame BB (overlooking the need for Campy thin or thick cups). But the middle of the BB spindle sold with the cups has be of the same width as the BB shell width. So for vintage, the spindle is what is not width-agnostic.

But as I was trying to say in my original post, I have never encountered a 73mm BB frame shell or a 73 mm middle-of-a-BB-spindle width before, no less a BB sealed cartridge of that width.

shelbyfv

Campy did make MTB components for a few years, may be some info in this link. MOMBAT: Campagnolo mountain bike component History

Velosiped126

Thank you for not being surprised despite not having encounter my Italian thread cartridge for a 73mm wide shell before. So I shall now go from confusion to acceptance: unless I measured wrong, it what it is although I have never seen this combo before.

Litespud

That was Euclid in the late 80's, but I don't believe that group used a cartridge bearing - still trying to get my head around an Italian-threaded 73mm BB

Litespud

I would be interested in seeing some pics when you can post them - I'm intrigued