While adding two optional standards to mountain bike wheel sizes may not be considered an explosion, it does complicate the industry landscape a bit more than the days when eight cog cassettes and 26in wheels were just a given. The advent of 29ers and later 27. 5in hoops has essentially cubed the choices available to off road cyclists. These options can get overly specialized for the indecisive cyclist however, for someone with a focus on pure, durable, XC speed, Niner's Air 9 Carbon 3 Star Complete Mountain Bike brings a long tire to trail contact patch, terrain devouring capabilities, and reliable, no frill kit to the singletrack network. It's a framewheel combination that demands speed a groupset that simply shrugs and carries on, regardless of trail abuse. The Air 9 Carbon carries a few more grams of weight than its RDO cousin, the latter of which places more of a Hollywood starlet's emphasis on losing weight at all cost. That doesn't mean the Air 9 is a Clydesdale, though the current iteration tips the scales at a more than reasonable 1,480 grams. Given that this is an actual weight for a size medium we weighed it ourselves and it's still only 400 grams heavier than the RDO's claimed weight, we won't begrudge the Air 9 Carbon those few extra grams especially since it puts the non RDO model in the self sponsored cyclist's price range. Everything else about the frame is the same as the RDO: the lines, the measurements, even the mold itself the only difference is that the Air 9 Carbon features a slightly heavier material and a less complicated lay up. Like the RDO, this frame's signature lines, which loop from the head tube through the bottom bracket and seat junction into the rounded rear triangle, aren't chosen for aesthetics. Rather, they're the product of extensive computer based finite element analysis aimed at minimizing chatter and guiding impact forces to the stronger parts of the frame. Chain torque goes directly to the rear wheel via the ov...