It's astounding that Niner continues to refine its longstanding AIR 9 Carbon Mountain Bike Frame, but there's no denying that the latest version is the best yet. It borrows both geometry and form from the race oriented AIR 9 RDO, and while it's not quite as light, it's slightly more robust as a result. That makes it perfect for larger, more powerful riders, or just those who push their 29er hardtails hard on a regular basis, and still appreciate a race capable machine that eats up miles of singletrack. The AIR 9 Carbon borrows heavily from Niner's AIR 9 RDO race rocket. At the core of every Niner frame is extensive computer based finite element analysis, and here it's used to develop a high modulus carbon fiber structure with optimized weaves, layups, and tube shapes. The weight saving measures haven't been taken quite as far as the featherweight RDO, but the AIR 9 Carbon is still adequately svelte. The swooping lines aren't chosen for aesthetics, rather they're designed to minimize chatter and guide impact forces to the stronger parts of the frame. Chain torque goes directly to the rear wheel via the oversized PF30 bottom bracket shell and shapely chainstays, while trail vibrations are damped by the swooping seatstays. Niner ties the bottom bracket to the precision enhancing tapered head tube via a large down tube to ensure the frame tracks true and responds to every input. Niner recommends an 80 to 100mm suspension fork, or a rigid unit with a 470mm axle to crown length and 45mm offset. Unsurprisingly, their award winning carbon fork shares those exact dimensions. Titanium plates are incorporated gracefully into the frame to protect against chain drop and chain suck. The tapered head tube comes equipped with a Cane Creek IS4228. 6IS5240 integrated Campy style headset. You'll need a 31. 6mm seatpost and a 35mm seat clamp. The rear triangle offers clearance for tires up to 2. 4 inches, although there are variances across tire manufacturers, so some of the ...