Bottom Bracket Help

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  • I'm trying to confirm required BB length for my 70's Dura Ace track cranks to give me a 42mm chainline. I fitted the cranks to a BB of known length (103mm on my Fuji - both JIS tapers?) and amazingly this gave a 42mm chainline. So, i'm assuming I can go with say a Sugino 103mm on the other bike I intend fitting the cranks to. I see from the transmission database most DA cranks are running 107mm BB's so I am assuming this applies to later cranks?

    If anyone can sense check what I've done please ...........

  • As long as you torqued the crank bolt up correctly, both tapers are JIS, and you measured the chainline properly, I think 103mm should be the same on one bike as the next, give or take a few 10's of microns for manufacturing differences.

    However! I bought a Sugino 103mm BB supposed to be the right size for a 42mm chainline with Sugino RD cranks and I seem to have about 44.5mm. But that's likely to be a manufacturing error with the crank rather than the BB.

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Bottom Bracket Help

Posted by Avatar for mowwog @mowwog

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