Shimano SM-CRM90 30T Replacement ChainringXTR SM CRM90 CHAINRING INFORMATION For some people, the most exciting aspect of the latest XTR iteration is that the cranks accommodate a modular chainring construction, which means the same crank can be used for a 1x, 2x, or 3x set up. If you opt for a 1x arrangement, and you like to have multiple choices in your toolbox, you can purchase each chainring separately. The Shimano XTR M9000 Chainring comes in four sizes: 30, 32, 34, and 36T.