It's a Direct Mount chainring so please use original lockring to mount it on the crank. Always use a new chain with a new chainring
If you wish to check for frame clearance with new oval ring, below you can find measurement of biggest dimension of the oval (tip to tip of tooth):
28T: 127mm ; 30T: 134mm ; 32T: 143mm ; 34T: 151mm
Other elliptical chainrings
Clocking (timing) and shape of the oval are the most crucial parts of the design. Ride quality of Absoluteblack Oval ring will be different to ovals from brand X or Y. 2 years of development of our ovals resulted in commercially most successful product of its kind. AbsoluteBlack is the First company who managed to successfully popularize ovals in mountainbike sport. Please note: Other manufacturers offer one timing and ovality setting for all chainring sizes, but pedaling behavior changes with each size considerably. To optimize for this, every chainring size needs to be a bit different. For example the smaller the chainring size the bigger the ovality has to be to help climb steeper hills more effectively. This is where we specialize in and optimize every size to particular pedaling style. This is also why we do not provide information about timing and exact ovality of the chainring as each one is different.
Using Hollowtech II BB Removal Tool (like BBB BTL-116 ), carefully open the lockring that holds the chainring on the crank(normal threads). Once the lockring is removed, take off old chainring, re-grease the splines on the crank. Place new oval chainring with convex side to the crank. Chainring/crank has special splines that only fit one way. Close the lockring to 35-50Nm of force. Chainring is only compatible with XTR CN-M9100 chains. Using other chains may cause chain to drop very easily from the chainring due to thinner than usual teeth.
What size should I choose?
Frame clearance (biggest dimension of the oval tip to tip of tooth):