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what size bottom bracket to get?(2 posts)

what size bottom bracket to get?joeblack
Aug 4, 2002 2:20 PM
Upgrading to ultegra 170mm crank 13-27 cassette.
what size bottom bracket do I need? What are they refering to when they say English or Italian?
Need more information.Spoke Wrench
Aug 4, 2002 2:36 PM
Bottom brackets have three significant dimensions.

The first is the thread. If your frame is anything common, it will have English threads. Guess what a very few frame builders, mostly Italian, use? To tell for sure quickly, measure the width of your bottom bracket shell. If it's 68mm or 73mm, it's English. If it's 70mm, it's Italian.

The second is bottom bracket shell width. Most road bikes are 68mm. Most mountain bike frames are 73mm. Your bottom bracket has to match.

The final factor is spindle length. The most significant factor in spindle length is the crankset. Whenever I buy a new crankset, the vendor that I use recommends the appropriate bb spindle length.

After going through all of that, if your Ultegra crank is one of the newer splined models, you need a 68 x 109.5 if it's a double and 68 X 118.5 if it's a triple.