BCD chainring confusion
 

I've got a 26 tooth aluminum 5 bolt chainring that essentially calculates to a 80 bcd (bolt center diameter). Initially I thought this ring would fit a 110/74 crank but it doesn't.

Any ideas on what kind of crankset this would go on?

What's the center-to-center measurement? I feel like it comes closer to 86, which would make this an obsolete chainring used on SR stuff.

Approximately 46.82 mm with my calipers. I actually went left edge to left edge to have a better visual gauge. I've attached a couple of photos - front and back. No markings at all on the ring. Weren't most inner rings steel? This one is aluminum.

I found this on a search but it's a 6 bolt.

Park used to make a great tool for this the CDG-1 I have not seen one in sometime check you LBS maybe they have one

PS; if anone who reads this thread knows what this tool is and where I can get it or a pic plz let me know

IIRC Dura Ace had a weird BCD on their very early triples, but I don't recall the BCD. All I recall was that it didn't fit anything else.

I think the Dura Ace triple BCD was 92mm, made for a 30 tooth inner chainring.