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Discussion Starter · #1 ·
I have a Faema NP (with steel fork), running mostly-Centaur 10sp ergopower groupset w/ double crank.

The crank was feeling a bit stiff (I'd been doing lots of rain riding w/ no maintenance) so I took it in a REI store for maintenance

They said that the bottom bracket felt crunchy, and needed to be replaced. (I kinda doubted that - but whatever.)

The problem is, they werent sure what to replace it with: They said I currently had a 111mm spindle width BB on it. I wanted Chorus, which the parts book (QBP?) listed at 111mm for "triple" and 102mm.

They said with my current 111mm BB, my chainline was very off. They postulated that the bike originally was setup with a Triple, and then swapped to a Double. Reason is, with the current BB, the 39t was sitting too close to chainstay, and using a "normal" 102mm - like its supposed to have - the small ring would rub.

The hesitation, combined with the fact that one mechanic (apron'ed) thought the thumb-shifter was a brake, and another didnt believe frame is 2005 model because it is steel, led me to go to an "LBS" where they determined I didnt need a new BB at all.

Anyway, the question is this: had I needed a new BB - what BB would be appropriate for my centaur double crank? What BB are you running on your NeoPrimato?
 
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It is an Italian BB so first off make sure they get that right.

The Centaur crank ( square taper ) takes a 111 mm in the double crank.

A Chorus or Record double takes a 102 mm axle length.

The difference comes about only because of the difference in the "Bow" cast into the two different cranksets.

If you know what crankset is on the bike, you know what BB to buy.

111 - buy the Centaur.

102 - buy the Chorus.
 

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Discussion Starter · #3 ·
terrific response - thanks!

shouldnt the measurement be the absolute distance from tip-to-tip? or is the "bow" you are talking about the taper depth from the tip? even so, one would expect that the measurement be "normalized" for consistency...

anyways, thanks again
 
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redfooj said:
terrific response - thanks!

shouldnt the measurement be the absolute distance from tip-to-tip? or is the "bow" you are talking about the taper depth from the tip? even so, one would expect that the measurement be "normalized" for consistency...

anyways, thanks again
If you look at a Chorus crank and a Centaur crank you will see a significant difference in the " dish" or the " bow" of the crank from the level plane.

That is what I meant and that is what the different axle lengths compensate for.
 
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