The stunning X Glide R™ chainrings are optimized for use with the YAW™ Technology in the front derailleur, delivering seamless, flawless performance. X-Glide R Chainrings The chainrings are designed for an optimized shifting performance with the Yaw front derailleur. The stiffer rings (5mm 7075-T6 aluminum CNC-machined) feature upshift rivets with an advanced design adopted from SRAM XX. CNC machining allows for precision control of each tooth shape, ramp, & nearly every shifting feature of the chainring. Chainrings, chain, & front derailleur are designed as a single integrated system for optimized performance. BB30 Besides serious weight savings, this bottom bracket means narrow Q-factor, more ankle clearance, greater bearing durability & stronger crank construction.