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For the purists.

It could be fairly easily argued that the 29-inch-wheeled hardtail is the fastest and most efficient mountain bike configuration out there. So what would make it even more so? How about letting the dedicated 29er masters, Niner, render one of such raw purpose that they slap their haloed Race Day Optimized moniker upon it? Then you wind up with the Niner AIR 9 RDO Carbon Mountain Bike Frame.

Far more than just a reskinning of the original AIR 9, the RDO is its own beast. Foremost were weight concerns, and extreme measures were taken to address them. For example, Niner relocated the rear brake caliper mounts with the sole purpose of saving weight in the form of a shorter hydraulic cable line. That's extreme. The company even ditched their proprietary CYA bottom bracket system - widely respected and even used occasionally by other manufacturers -in favor of the lighter PressFit 30 interface. These details, in conjunction with the frame's aggressive geometry, indicate the seriousness of Niner's mission to craft the ultimate race-ready hardtail.

But let's look at the bigger picture, too. Niner started from scratch and revisited the computers to take another look at the AIR 9's carbon layup via finite element analysis, or FEA. They reconfigured the structure of the frame completely, developing new carbon weave patterns and utilizing new tube shapes to stretch every gram of material to its maximum without compromising strength or durability. The heavily curved and contoured shapes you notice - most notably in the top tube and seat stays - are purposeful, intended to mitigate excessive vibration and impact from the trail, while the stout down tube, chain stays, and tapered head tube are dialed to channel every watt and nuance of rider input into the wheels.

The RDO uses a 31.6mm seat post and a high-mount, bottom-swing, and bottom-pull front derailleur with a 34.9mm clamp. The rear triangle provides clearance for tires up to 2.4in, and staying true to its XC nature, the AIR 9 RDO only uses 160mm rotors, with the caliper attaching via a post mount. Niner recommends a maximum chainring size of 26/39t for SRAM or 28/40t for Shimano for two-by applications in order to avoid interference issues. Any traditional triple setup will also work fine.

Niner recommends 80 to 100mm suspension forks, or for the lightest setup possible, a rigid unit with a 470mm axle to crown length and 45mm offset. Perhaps not coincidentally, Niner's award-winning carbon fork shares those exact dimensions. The tapered head tube comes equipped with a Cane Creek IS42/28.6 | IS52/40 integrated (Campy style) headset. For those who intend to run a one-by drivetrain, such as SRAM's XX1, the AIR 9 RDO will clear up to a 32t ring, with a 168mm Q-factor crankset.

The Niner AIR 9 RDO Carbon Mountain Bike Frame - 2012 is available in four sizes from Small to X-Large and in the color Licorice.

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  • Q & A

What do you think about this product?

Have questions about this product?

LOVE this frame.

  • Familiarity: I've put it through the wringer

I paid $2,000 for my XL frame a couple of years ago, and it is still going strong. It is a quality carbon frame. With a top of the line XX1 build and Easton EC90 wheels it weighs 20 lbs even. In the fall, this frame does double duty as a cross bike, I throw on a rigid Niner carbon fork and lightweight tires and it weighs only 17.5 lbs, which is actually lighter than my carbon/Ultegra road bike.

I suspect that there are a couple of reasons why this frame is on mega clearance: first, the big XL size doesn't fit many people. It fits me great, I'm 6'3" and 180 pounds. The second reason is that I suspect that very soon Niner will be updating this frame to the 142mm rear axle standard. This may not bring any weight savings, but will be an update to fit in with this trend of the marginally stiffer 142mm thru-axle. I will be riding this frame for a few more years before seeing any need to upgrade, it is holding up great.

Hello - will this bike take an xo1 set up...

Hello - will this bike take an xo1 set up 10x42?


That is a great question. You should have no problems running xo1 set up with 10x42 cassette, but a 34t chain ring and bigger will give you compatibility problems. If you have any additional questions, please feel free to email me at

I have the XX1 156q crank, will this not...

I have the XX1 156q crank, will this not clear? Also, 32t as the largest gear in a 1x, no clearence to go to a 34 or 36? This might be a deal breaker for me. Love the frame and price though!

Unfortunately, an XX1 156q factor cranks with a 32t chain ring will give you problems on that frame. Even though the Niner Air 9 is one of our favorite bike frames, it can have some compatibility restrictions. Feel free to contact me to discuss any other frame options that may be a better fit for your needs and I will do my best to help.

I just bought this frame, and while building...

I just bought this frame, and while building it the rear chain stay protector fell off in my hand (!!) How do you re attach? The sticky tape isn't sticky enough to re adhere to the frame

Would really like to buy this frame... but...

Would really like to buy this frame... but does it have a meduim? My query also goes to Air 9 carbon. And are you shipping items to Courtenay BC. Please respond, many thanks!

Best Answer

At the time of this posting, it seems that the only size frame that BC is stocking currently is a size XXL. Also, there are certain brands that BC cannot ship outside of the US; unfortunately, Niner would be one of those brands. For a complete list, I've included a link to the brands that Backcountry can and cannot ship if you want to view it for yourself in case you have anymore questions about a particular item, and whether or not it can be shipped to Courtenay, British Columbia. ( Best of luck, sorry to be the bearer of bad news.