The SRAM XX1 BB30 Direct Mount 156 Q Factor Crankset brings race worthy power transfer and renowned chain retention to drive any trail adventure. While opinions on direct mount and bolt on chainrings may be mixed, we're on board when it comes to the weight savings gained with the direct mount system.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 single ring setup. The X SYNC chainring is designed for maximum chain control, with each tooth being CNC machined in order to support the 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. SRAM even went as far as to say that you have a better chance of dropping your chain with a front derailleur than you do with the XX1 crank and chain combo.The XX1 BB30 Direct Mount Crankset is compatible with BB30 bottom brackets and direct mount chainrings.