Niner's Air 9 RDO 4 Star X01RS 1 Complete Mountain Bike won't transform you overnight from a baggy shorts noodler into a Lycra clad rocket however, if you've already built an explosive fitness level, then the Air 9 RDO's Carbon Compaction System CCS layup and X01 one by drivetrain form an appropriate catalyst to propel you into the XC firmament. The frame's rocket ship status is a result of Niner's Race Day Optimized RDO construction ethos, which removes any impediments to speed. This begins with the CCS construction method mentioned above, Niner's proprietary method of compacting carbon to eliminate any extra material, resin pooling, and imperfections for a virtually perfect frame that's a claimed 100 grams lighter than the previous Air 9. The obsessive reworking of the frame is even evident in such details as the low profile disc brake mount and the omission of the usual, heavy CYA bottom bracket in favor of a PF30 model. Despite these changes, though, the Air 9 RDO's race proven geometry and tube shapes, designed to dampen chatter and distribute impact forces to the stronger parts of the frame, remain largely unaltered. Chain torque goes directly to the rear wheel via the same large bottom bracket shell and shapely chainstays of previous models, but with the added stiffness of a 12x142mm rear axle. The bike's spine connects the tapered head tube to the oversized bottom bracket via a large down tube to ensure the frame tracks true and responds to every input. In order to keep your mind off of ancillary concerns and focused on the race, Niner specs this model of the Air 9 RDO with their 4 Star build. A quick glance at the spec sheet suggests that the these are the SRAM X01 drivetrain, the RockShox RS 1 Solo Air fork, Stan's NoTubes ZTR rims mated to SRAM's XO hubs, and Shimano's indefatigable XT M785 brakes.