DUB bottom bracket (not included) adds durability and simplicity X-Range gearing technology gives you more range and a smoother gear progression, so youre always in the right gear Crisp and accurate front shifts Unique chainring design results in a lighter weight, stiffer, more durable crankset Carbon crank arms and aluminum chainrings are lightweight The SRAM RED AXS crank uses an important design innovation: smaller chain rings and a wider cassette spectrum. In order to provide exceptional cadence and efficiency, the range has been moved from the front of the drive strand to the rear area, creating a consistent gap of 13 teeth for all variants of chainring duos. The crankset is specially designed for the electronic circuit and can be upgraded to a power meter.