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  1. #1
    RoadBikeReview Member
    Join Date
    Aug 2009

    DA 7800 crank arms to replace Ultegra 6703

    I have access to a pair of Dura Ace 7800 170mm crank arms and would like to replace my Ultegra 6703 175mm crank arms...Both are 130 BCD and apparently the granny ring on the 6703 attaches to the middle ring, not the spider...Is this possible or do I need a dedicated triple spider such as a 7803?....Thanks

  2. #2
    Reputation: metoou2's Avatar
    Join Date
    Mar 2009
    Are you confident that the switch to 170mm won't be problematic for you?
    This mssg brought to you by Mr. Bananas.

    Shouldn't it be called a 'nipple wrench'?

  3. #3
    wim is online now
    RoadBikeReview Member
    Join Date
    Feb 2005
    Not 100% sure, but I can't see a reason why it shouldn't work. Both 6703 and 7803 triple crank inner rings have a 92 mm BCD and both attach to the middle ring. I strongly suspect that this arrangement was chosen to keep the spider configurations for the doubles and triples identical. Since you insert a spacer between the left crank and the BB cup with the 7803 but not with the 7800, I would think that axle length is slightly different between the 7800 and the 7803.

    Don't know why a 5 mm difference in crank length should be "problematic." It has never been shown that crank length makes much of a difference at all to performance.
    Last edited by wim; 12-27-2012 at 05:48 AM.

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