Originally Posted by
zacster
In the old 5 arm days, the bolt ring diameter was different between full and compact sizes. 130 vs. 110 I think.
Five-arm cranks came in a large number of bolt circle diameters, including 86, 94, 110, 118, 120, 122, 128, 130, 135, 144, and 151mm; maybe a few more I missed. But most recently 110 and 130 are the most common for road cranks.
I have no idea with the newer stuff. Also, the old rings were compatible across brands. I never knew what was wrong with that.
Yeah, there's all kinds of mutually incompatible stuff these days as well. You know what they say: the nice thing about "standards" is you have so many to choose from!