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PostPosted: Wed Dec 30, 2009 9:19 am 
Newbie

Joined: Tue Dec 01, 2009 12:10 pm
Posts: 6
Hi all, I have a conundrum as my new De Rosa SLX frame seems to have a different BB diameter than my Colnago Master Olympic and the Record BB that I have doesn't fit, it just slides straight through (ie the De Rosa is a larger diameter)

Now this is the first time I have come across this, with any bike other than a Cannondale with BB30, I always thought that the diameters of the BB's of all road bikes were the same (normally the thread may be different - Italian vs English) but this is just wierd......

Did they change the diameters of the BB's when they moved to cartridge BB's (ie sealed units) or something, as I think the DeRosa is older than the Master O.

Can anyone help me out here ??? Confused indeed......

Thanks
Sean


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PostPosted: Wed Dec 30, 2009 9:43 am 
retrobike rider
retrobike rider
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Joined: Fri Aug 08, 2008 2:36 pm
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Location: Yorkshire, England
Italian bottom bracket. 70mm wide ? it is also a larger shell.

My best guess.


edit
err i'll add this
http://www.sheldonbrown.com/gloss_i-k.html#italian
oh and this
http://en.wikipedia.org/wiki/Bottom_bra ... _threading


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PostPosted: Wed Dec 30, 2009 10:22 am 
Newbie

Joined: Tue Dec 01, 2009 12:10 pm
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Well that explains it, but what it doesn't explain is why does the BB fit my Colnago ??? Wierd.....

Thanks heaps


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PostPosted: Wed Dec 30, 2009 11:30 am 
retrobike rider
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I know nothing about these bikes, but probably because it just uses a different size bottom bracket ;) e.g. the one you have ?

or am I missing something :xmas-big-grin:


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PostPosted: Wed Dec 30, 2009 12:16 pm 
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Because one would assume that the diameter of my Italian Colnago and Italian De Rosa of similar vintages would be the same !


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PostPosted: Wed Dec 30, 2009 2:55 pm 
Retro Guru

Joined: Sun Aug 03, 2008 12:31 am
Posts: 585
Location: London
It seems your De Rosa has a British threaded BB and your Colnago has Italian.

AFAIK all Colnagos have an Italian BB, dunno about De Rosa though.

An Italian BB shell is both larger in diameter and width.


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PostPosted: Wed Dec 30, 2009 3:36 pm 
Newbie

Joined: Tue Dec 01, 2009 12:10 pm
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This is what is wierd, its definitely Italian, 70mm wide but 36mm diameter. My BB is also Italian

But a smaller diameter. Do Italian BB's come in different diameters ?


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PostPosted: Wed Dec 30, 2009 3:52 pm 
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Joined: Tue Dec 01, 2009 12:10 pm
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Doh.....idiot !!!!! (me that is) of course the De Rosa is Italian....the problem is ....well.....my "Italian" BB is......well, kind of English.....

Mystery solved, thanks for all your help guys. I'll just go and boil my head. What a muppet !


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PostPosted: Wed Dec 30, 2009 3:58 pm 
Old School Hero

Joined: Wed Mar 19, 2008 6:52 pm
Posts: 204
Location: Northampton
I have a similar question and am eagerly awaiting a conclusion.
I only new the thread and width of body were different and obviously the axle length depends on what cranks you intend to fit. From what you say it does seem that the diameters differ as well. I will have to borrow a caliper to check what I took off.
Does the age of the frame prehaps have a bearing on Diameter?


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PostPosted: Wed Dec 30, 2009 5:25 pm 
Retro Guru

Joined: Wed Nov 04, 2009 9:57 pm
Posts: 641
the other difference is that the italian b/brackets are both R/hand threads on both sides of the b/bracket
english are l/hand on the chainwheel side and r/hand on the crank side


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