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Replaced Shimano Bottom Bracket, now front derailleur won't shift to largest gear

How do I measure a bottom bracket?

I thought the only thing that mattered when replacing a bottom bracket was the thread size (68mm) and the spindle length. - unsavory

Me too. I had thought that the things to consider are:

  • Thread specification e.g BC 1.37 x 24, English or Italian
  • Thread width: 68 or 73mm
  • Cranks interface
  • Spindle length e.g. 113mm

And now it turns out the axis offset matters. How do I determine this before purchase. E.g. in this datasheet there is no mention if the axis is symmetrical or offset.

When should I be worried about unsymmetrical BB spindles and where should I check to ensure compatibility?

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Adjusting the derailleur won't work? –  Alexander Oct 16 '13 at 20:05
    
@Alexander, I mean before purchase. How do they denote non-symmetric BBs? A couple of examples in datasheets, for example. –  Vorac Oct 17 '13 at 10:29
    
Sorry, my English is pretty bad (so maybe I didn't understand what you wrote), but when you choosing a BB, you have to look also at the length of pin that in chain side (if you want to avoid adjusting derailleur). "113mm" as you wrote is the full length of BB. –  Alexander Oct 31 '13 at 21:59
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1 Answer 1

With Shimano there are "E" and "K" variations of bottom brackets that refer to coaxial mounted front derailleurs and chain guards respectively. The BB variations provide for enough space on the drive side spindle to build in another "ring" of the derailleur or the chainguard carrier.

For exact paramenters Sheldon Brown could be helpful too. http://sheldonbrown.com/bbdrop.html

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I'm vaguely recalling that a Phil Wood site lists some BBs and their dimensions. –  Daniel R Hicks Nov 18 '13 at 23:35
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