ninjanoir78

hi, do you think I can put a cannondale chainrings (the Si hologram) on my dura ace 7800 crank??
and/or put the dura ace 7800 chain rings on my si crank??

thanks

AngryScientist 

bcd

joejack951

Most likely. Almost all road cranks these days are 130mm BCD for all rings but the granny on a triple, as Angry subtley alluded to. Campy uses 135mm BCD and a few high end cranks have used other non-standard BCDs but I don't believe your Si crank is included in that category. Zipp and Stronglight come to mind as companies that have ventured off the beaten BCD path for one reason or another.

thegunner

but but but... stronglight TA rings are slightly thinner than sram red crank arms, so while it'll fit, it's not a perfect fit.

edit: just adding that not all rings are compatible with all crank arms

joejack951

That's a good point. The mounting flanges on all cranks are not the same thickness and neither is the tooth centerline to mounting flange distance. You'd be effectively changing your chainline if the rings did not have an identical tooth centerline to the originals.