Lots of jargon to go through in explaining the SRAM XX1 Eagle Boost BB30 Crankset. SRAM, you know. XX1 is the top-of-the-line single-ring designation. Eagle refers to their 1x twelve-speed system. Boost refers to a hub standard which necessitates a different chainline. BB30 is a bottom bracket standard.
Boost is a new wider hub standard that is taking off, and largely found on Plus bikes. Because the hub is wider, the cassette is moved rightward, which means the chainline needs to be moved as well. The chainline is moved 3mm to the right, for a total of 52mm from the bike center.
The chainring is the only change from a standard Eagle XX1 BB30 crank. The axle width stays the same, the crankarms stay the same, the Q-factor stays the same.
That axle width and diameter is set for BB30 and PF30 bottom brackets. The width is set for BB’s 68 or 73mm wide, and the axle diameter is 30mm. That 30mm diameter limits the bottom bracket standards the thru-axle can work with. You might be able to use a conversion bottom bracket to put this crank in a threaded bottom bracket shell, but that’s beyond SRAM’s recommendations.
What really sets this crank apart are the arms and the Eagle twelve-speed chainring. The arms utilize a new technology called Carbon-Tuned. It’s a precise wrapping of different plies around a hollow core to maximize stiffness and minimize weight. No reason to carry the bulk around if you don’t need it. The stiffness-to-weight ratio is unrivaled.
Helping save weight, add drivetrain efficiency, and improve that all-important simplicity, are the direct-mount chainrings. Held by T25 Torx bolts and several splines, the X-Sync 2 rings bolt into the right crankarm. They’re forged and CNC-machined aluminum with a new tooth profile. SRAM found that most chainrings basically hold the chain at the first few teeth where the chain meshes with the ring. That leads to wear and inefficiency. So the new design holds the chain all the way around. The teeth are designed to not only keep the chain on with an alternating tooth profile, but the positive-rake teeth also held mud and grit come out of the chain as it moves around the ring. Sizes are 30-38 teeth in two-tooth increments. Did we mention quiet? They’re super-quiet.
The X-Sync 2 rings are designed to work with Eagle twelve-speed chains, but can be used with SRAM 1x 11-speed systems. If you’re coming from a 1x eleven-speed, go with a two-tooth larger chainring to have both a higher high and lower low than you did before.
The SRAM XX1 Eagle Boost BB30 Crankset offers you the lightest way to set up 1x on your Boost BB30 bike.
Sram XX1 Eagle Boost BB30 Crankset
- Brand: SRAM
- Product Code: sg156
- Availability: In Stock