Originally Posted by
schnurrp
Yes, but my Shimano SORA crank set has both the outer 52t and middle 42t rings attached together at the end of the five spoke crank with bcd 74mm. The inner 30t has its own attachment point on the spokes at about 43.5 mm bcd.
I think you must be misinterpreting the measurements. I'd suggest looking at Sheldon's page I linked above. Are you measuring the distance between two adjacent holes, and getting about 74mm for the large set and about 43.5mm for the smaller set? That corresponds to a pretty standard road triple crankset where the smaller set has a 74mm BCD (bolt circle diameter) and the larger set has a 130mm BCD. It sounds like you're measuring between two adjacent holes, and not the bolt circle itself.