Spot the difference - M770 32T chainrings

[Fatmat]

Hi guys, any idea why these 32T M770 middle chainrings are different? Mine have holes around the outside, the other one doesn’t! Both from a FC-M770 chainset, I’m guessing there’s a variant / different year! Can anyone explain? Thanks, Matt

 

[hamster]

I suspect one was an OE version, the one with holes is aftermarket.

 

[robfinger]

The holy one is more modern? On a steel ring with that many teeth to spread the load from the chain there's little chance you'll be shearing them off during extra hard pedaling, so it makes sense to shave a bit of weight that way. Or you can have an aluminum ring instead but those do wear faster and Shimano has traditionally gone for the long-life stuff.

 

[FluffyChicken]

No expert on these, is the ring darker on the one with no holes?
XTR had no holes.
XT/SLX had holes.

But who knows, is it still steel (no holes)?