AIR 9 RDO X01 Eagle Complete Mountain Bike
Nothing beats the raw efficiency and climbing prowess of a lightweight hardtail, and it's also nice to have a little compliance to mute the trail when times get rough. For those of us who love to toe the line, get hypoxic, and possess the handling chops to deftly navigate rock gardens at speed, hop aboard the AIR 9 RDO X01 Eagle Complete Mountain Bike and enjoy an unfair advantage. With progressive geometry and Boost spaced axles, this AIR is ready to rip it on race day or KOM hunts. This build takes Niner's Race Day Optimized carbon frame and kits it out with SRAM's XO1 Eagle one-by drivetrain and hydraulic brakes, a plush and lightweight RockShox SID RLC fork, Niner's carbon fiber RDO post, and an all-French affair for the rolling stock consisting of Mavic XA Elite wheels wrapped in fast rolling, yet grippy Michelin Force AM rubber.
Keen eyes might notice that the most notable changes to this in-house build versus a Niner one is the addition of 20mm more travel at the fork. We feel the benefit here is the fork is going to weigh the same anyway, so why not take advantage of slackening the headtube angle from 70-degrees with a 100mm fork to 69-degrees with a 120mm making the bike a lot more fun on trail rides. Paired with that long reach, the bike rides with plenty of stability on fast wide open sections and can quickly transition to change lines on tight singletrack, i.e. ideal handling manners for a race machine. Compared to the previous Air 9, the chainstays shrank by 4mm to 435mm for quick acceleration and nimble handling without feeling nervous at speed.
The Air 9 RDO also has a skinny seatpost diameter of 27.2mm to take advantage of that little bit of extra flex and resulting comfort found in a smaller diameter 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, 12 x 148mm Boost axle spacing stays 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 chainstays are 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 flat out looks better too.
As with Niner's other RDO offerings, the Air 9 RDO is constructed using Niner's Carbon Compaction System (CCS), which gives Niner complete control over tube wall thickness across the frame. This makes for tube walls that are virtually perfect, reduces the number of materials required, and eliminates excess resin build-up. The result is a claimed 10% weight reduction over previous editions which is great to know when you're giving it your all on the last climb on course.
- A race-bred XC hardtail that likes trail riding too
- Modern XC geometry takes on more technical courses
- Lightweight RDO carbon boosts stiffness in the right places
- 12 x 148mm Boost axle spacing increases responsiveness
- 120mm of RockShox squish softens the blow from the terrain
- Smaller diameter 27.2mm seatpost offers a touch of compliance
- SRAM X01 Eagle provides a massive gear range and reliable shifts