When buttery smooth trails transition to the rough, it's nice to have a little bit of squish up front to soften the ride. For those of us who love the adrenaline rush of deftly navigating rock gardens and live for a big dose of hardtail speed, Niner brings the 2017 Niner Air 9 RDO 5 Star XTR 1x Complete Mountain Bike to the table. With tweaked geometry and boosted axles, this whip is ready to rip. As the name implies, this build sits at the top of the Niner pyramid, kitted out with Shimano's top end XTR one by drivetrain and hydraulic brakes, a show stealing RockShox RS 1 fork, Niner's carbon fiber RDO post, and a set of smooth rolling carbon fiber hoops wrapped in versatile Maxxis Ikon tires. The most notable changes to the frame include a lower handlebar height, giving the Air 9 a nudge towards the venerable RKT 9 RDO's aggressive positioning. It has a longer cockpit and slacker head tube, making for a frame that handles deftly on knife edge lines and jumps the second you need it to. Compared to the previous Air 9, the chainstays scrunched in by 4mm to 435mm for lightning fast acceleration and nimble handing without crossing over into jumpy, squirrely territory. The new Air 9 RDO also sizes down its seatpost diameter to 27. 2mm to take advantage of that little bit of extra flex and resulting comfort found in a narrower post. Niner pushes this benefit to the max by pairing this frame with its RDO Carbon Fiber Post, which is specifically trail tuned to provide additional flex to soften the ride. Out back, this year's model now boasts a 12 x 148mm Boost axle width, keeping in line with current trends for wider axles and stiffer wheelsets. Niner also tucks the brake caliper mounts on the chainstay, neatly within the rear triangle. This makes sense from a frame building standpoint, as the seatstay is generally the burlier of the two rear stays and the placement protects the caliper somewhat in the event of a crash. We also think that particular placement just l...