The trick with 104 BCD is that it's the workhorse spider standard for pre-Transmission SRAM Eagle 1x builds — and Shimano and third-party crank spiders too — which means when your original chainring is worn out or you want to change tooth count, you're not locked into buying a whole new crankset. SRAM's X-Sync 2 Eagle 4-bolt chainring uses a 104mm BCD, is crafted from CNC aluminum, and is designed for use with SRAM Eagle 12-speed chains . It fits any 104 BCD crankset, including Quarq's XX1 Eagle power meter spider and power2max MTB spiders, which is why this is the ring most riders end up on when they're adding power measurement to an existing Eagle drivetrain.

Compatibility runs across SRAM 11- and 12-speed drivetrains, but it is NOT compatible with the Eagle Transmission T-Type chains . That distinction matters: if you're running GX, X0, XX, or XX SL Transmission, you need a T-Type chainring, not this one. If you're running the previous-generation Eagle ecosystem — NX, GX, X01, XX1, or AXS pre-Transmission — this is the ring designed for your chain.

The tooth profile is a direct result of SRAM's engineers studying performance and wear characteristics of thousands of original X-Sync chainrings, and the longer, positive-rake tooth shape is designed to work with the Eagle chain to increase chain retention and pedaling efficiency while decreasing friction, noise, and wear . The sharp and narrow tooth profile, along with rounded chamfer edges, help manage a deflected chain — meaning when you're pedaling through rough terrain and the chain gets knocked off-line, the teeth are shaped to keep it engaged rather than dropping it.... Read More