# Ultegra 6600 vs 6603 Chain Rings



## shooker (Dec 29, 2009)

Hi,

Will 52/53T outer and 39T inner 6600 chainrings off a double set-up fit on to 6603 as outer and middle on a triple set-up?

Thanks


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## RussellS (Feb 1, 2010)

Yes the 6600 rings will fit onto a 6603 crankset in the outer and middle positions. They all use 130 mm bcd. Only problem is the 6600 39 tooth ring will not have pins to help it upshift from the inner ring to the new middle ring. So shifting from inner to middle will likely be slower. 6603 middle rings are specifically built with pick up pins to help upshifts from the inner to middle rings.


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