Direct power transfer.
The SRAM XX1 BB30 Direct Mount 156 Q-Factor Crankset brings race-worthy power transfer and aggressive chain retention to any trail adventure. While opinions on direct-mount and bolt-on chainrings may be mixed, it's hard to argue with the prospect of weight savings and increased stiffness. This crank's 156mm Q factor is SRAM's narrow option, so it's ideal for drivetrains and rear linkages that don't create clearance issues. It's more biometrically sound, but it can also literally encounter problems (in the form of encountering chainstays) if a bike has a wider back end.
The carbon fiber arms are paired with a CNC-machined aluminum chainring for a lightweight crank arm that doesn't require a finessing of parts in order to make an optimal one-by setup. The X-SYNC chainring is designed for maximum chain control, with each tooth being CNC-machined in order to support the XX1 chain's inner- and outer-links.
This machining process provides a variable thickness from tooth-to-tooth, so the chain and chainring essentially lock together as you pedal. However, the locking of the two doesn't inhibit pedal efficiency, and it eliminates the commonplace ailments associated with running a single-ring up front. Additionally, this system provides you with a liberation from chain guides. Since the chainring never has to surrender chain control to a derailleur, it's built to retain it jealously, so double cranksets (which do have to yield to derailleurs) have a much higher chance of throwing a chain.
The XX1 BB30 Direct Mount Crankset is compatible with BB30 bottom brackets and direct-mount chainrings.