Worn teeth on a 1x chainring rarely mean the whole crankset needs to go. SRAM's X-SYNC 2 chainring bolts to any 104mm BCD 4-bolt spider, so riders running older XX1, X01, X1, X9, or aftermarket 104 BCD cranks can swap a fresh ring on without touching the crankarms or bottom bracket. The 104mm bolt circle is the long-standing standard SRAM used across the Eagle-compatible spider lineup, which makes this ring a clean replacement path for a lot of higher-mileage drivetrains.

The X-SYNC 2 tooth profile is what separates this from the original X-SYNC design. The teeth are longer with a positive-rake shape, narrower to match the inner plate spacing of 12-speed Eagle chains, and rounded at the chamfer edges to manage a deflected chain when the cassette is at its extremes. Wide and narrow teeth still alternate to lock into the inner and outer link openings, but the updated geometry holds the chain through the engagement arc rather than just at the top of the ring. That matters most on rough descents and high-torque climbs, where a chain that releases cleanly off the back of the ring is the difference between quiet pedaling and the slap that signals a dropped chain is coming.

One thing to confirm before ordering: this is the 4-bolt 104 BCD version, not the 3-bolt or 8-bolt direct mount X-SYNC 2. If your crank uses SRAM's direct mount interface — anything with a spline pattern instead of a bolted spider — you need a different ring. The 4-bolt version is for cranksets with a removable spider or dedicated 104 BCD arms.... Read More