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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 10-20-05, 07:23 AM   #1
askrom
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My frame is a 1989 Olmo, so I figured the BB threading might be Italian. So I measured the BB and it came out to 68mm, not 70mm which is the Italian standard. Everything I've read says that 68mm is English threading and that 70mm is Italian. So when I got a new BB, I got it with English threading. Now I've removed the old BB, and as I try to insert the new BB, it doesn't fit. The English BB is too small. Oops, I'm Italian! Damn.

I guess I didn't want to bother removing my old BB to check the thread direction (clockwise/counterclockwise) after having confirmed the very clear 68mm width. I should have, though, because yes, I did remove both cups with the same counter-clockwise rotation. That's not English threading, apparently.

I've checked Sheldon Brown's charts, and re-checked them today.
http://sheldonbrown.com/gloss_bo-z.html#bottom

So my questions are twofold, both regarding my 68mm bottom bracket shell measurement.
1) Is it likely that my threading is Italian, as I now assume it is, or could it be something entirely different?
2) Will a "normal" 70mm Italian BB work in my 68mm shell? Do I need like a pair of 1mm spacers or something?

Thanks!

PS: I think I'm doubly screwed here. My new crank is a Truvative Roleur, which has an integrated BB spindle on the drive side. So to replace the BB, I'd somehow need to find just the cups to fit my frame. Yt I've only ever seen the crank sold with the BB included. Can I buy just the BB parts for a crank with an integrated BB? Where would I go for such stuff?

Last edited by askrom; 10-20-05 at 07:39 AM.
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Old 10-20-05, 07:29 AM   #2
sydney
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Consider the shell might have been faced a few times, or off spec in the width to begin with. The 70mm shell width is not engraved in titanium. It's the thread diameter,pitch and direction that matters. The Italian BB you got will work. I've even used 68mm BB in 73mm english shells.
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Old 10-20-05, 08:29 AM   #3
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To get the cups first try the company you got the crankset from. If that does not work try Truvativ. They are owned by Sram. www.sram.com
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Old 10-20-05, 08:38 AM   #4
askrom
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I got it off ebay. Still, I think I've found a couple of places that sell the cups separately. Thanks!!
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Old 10-20-05, 08:18 PM   #5
John E
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That's the first time I have ever heard of 36x24 cups with a 68mm BB shell width, but there is no reason except tradition that it couldn't be done that way.

Thanks for blowing my standard advice to measure BB shell width to identify Italian BBs.
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