I want to change to a 165 mm crank length on the drive side of my Dura Ace Octaplus FC7703 triple chain set. Can I use a drive side Dura Ace Octalink FC7710 track crank to do this? Are the two crank sets compatible? Thanks

  • 2
    Are you saying you want to change the drive side crank arm only? Jun 26 '20 at 9:53
  • OP question is very confusing. As AA comments, what exactly is OP trying to do? Keep FC7703 triple chainrings on drive side but go to 165mm crank arm length on that side only? More details and some indication of goal would be very helpful here.
    – Armand
    Jun 26 '20 at 14:28

The FC7703 triple crankset uses an Octalink 118.5mm bottom bracket

The FC7710 track crankset uses an Octalink 110mm bottom bracket

If you want to use the track crankset, you would need to change the bottom bracket to the correct one.

PDF for triple crankset

PDF for triple bottom bracket

  • 2
    I believe the spindle length difference is due to double vs. triple chainring mounting in this case. If OP could transfer the FC7703 triple chainrings to FC7710 (this can NOT be done because of different BCD), the 118.5mm spindle length might be appropriate because the granny gear is mounted directly on the middle ring, not the crankarm.
    – Armand
    Jun 26 '20 at 14:58

It looks like the FC7710 chainrings are 144mm BCD (from ebay chainring Y16S45001 listing) while the FC7703 has BCD 133mm (from ebay listing https://www.ebay.com/c/15025379322 ) Thus, OP could NOT replace his drive side FC7703 crankarm with a FC7710 165mm crankarm and transfer the chainrings over.

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