After much speculation and considerable delay, Shimano unveils the final piece of the XTR puzzle: a chain-retaining single ring.
Shimano XTR Di2 drivetrain with the new chain retaining tooth profile
Shimano’s new XTR chainring doesn’t have a narrow/wide tooth profile like that used by SRAM and Race Face, and the teeth aren’t wavey like MRP’s patent swerving design either. Instead, the lead edge of each tooth on the Shimano XTR chainring hooks forward, ever so slightly, to hold the chain in place.
Shimano XTR Di2 single ring with Dynamic Chain Engagement
In addition to eliminating the need for some sort of chain device to stop derailments, Shimano claims that its unique tooth profile reduces wear and noise when compared to a narrow/wide design.
Dynamic Chain Engagement
Shimano’s product code for the new chairing is SM-CRM90 and it uses a custom 4-bolt mounting pattern that’s unique to XTR chainsets. The new chainring is available in 30, 32, 34 and 36t sizes, where the 30t and 32t rings get Titanium teeth and an aluminium body, while the 34t and 36t rings benefit from Shimano’s hollow chainring construction, first introduced on its road bike chainrings to boost stiffness and reduce power loss. All XTR single rings cost £89.99 and are available now through Shimano dealers. The new chainrings can be found on both mechanical versions of XTR as well as the electronic Di2.