glucany

Hi everybody. I have an Ultgegra triple groupset 9 speed; I need to change the crankset mod. 6503 because its too long 175mm, I need 170mm at most). Can I just substitute it with a Dura Ace triple crank 7703?
Thanks a lot for your help.
Luca

Al1943

Yes, but you cannot switch the middle or smallest chainrings due to the way the smallest ring is attached to the 7703 crankset. The middle chainring on the 7703 is a 39, the middle ring on the 6503 is a 42. If memory serves me, the big ring on the 7703 is a 53, the big ring on the 6503 is a 52. The 7703 front derailleur should work better with the 7703 crankset due to the 14 tooth jump from the middle to the big ring. If you don't have the 7703 FD and you don't like the shifting could try the Ultegra 52 big ring on the 7703 crankset. Try to get the 7703 FD.

glucany

Thank you very much, you've been very helpful! I'll install the 7703 crankset and see how it goes; if needed I'll try your two suggestions. Thanks again.

mudboy

You need an Ultegra triple front derailleur with the Ultegra crank, and a DA FD with the DA crankset because the FD's are tooth-difference specific. Ultegra works with 42-52 and DA works with 39-53. I've tried to make it work, and it doesn't.