Niner AIR9 RDO hardtail gets lighter, stiffer and more aggressive

The original Niner AIR9 RDO was the second generation of their carbon hardtail AIR9, which was known for its spine rattling stiffness. The RDO, then, was made not just lighter, but also more compliant with the goal of making it more comfortable than the original.

But, Niner says that reworking of the layup also resulted in less lateral stiffness than a top-level race hardtail should have. While it was no slouch in our own testing, the chance to rework it also opened up opportunities to make it lighter and modernize the geometry. Borrowing the long, slack “XC” geo from the recently introduced RKT9, the all-new 2017 Niner AIR9 RDO gets some big changes and an impressive 10% weight reduction…

To retain the improved comfort of the first RDO and improve performance, they essentially split the frame into top and bottom halves. The top adds compliance with thinner top tube and seatstays, and the seatpost drops down to a 27.2 diameter.

They slackened the headtube a full degree to 70° with a 100mm fork and stretched the front center slightly. The revised geometry also allowed for improved fit by making the headtube up to 20mm shorter on smaller sizes. That means their racers no longer need to slam the stem or remove dust caps to get low enough, and all sizes put the rider in a more aggressive position.

Down low, the frame is optimized for stiffness and snappy acceleration by way of an broad downtube and full width bottom bracket shell, which leads into…

…Boost 148 rear axle spacing. The extra axle width let them chop 4mm off the chainstay and bring them down to 435mm while also bumping chainring capacity up to a huge 38t on a 1x setup (up from 32t).

It also made room for a health 2.4″ of rubber with space to spare. They could have made the chainstays shorter but said 435mm was the right length for stable handling and proper rider weighting while climbing.

Frame weight came down a whopping 10% on average. Old frames averaged about 1,180g, these are hitting about 1,050g with hardware, seat collar and derailleur hanger, plus paint and protective tape. The only thing that weight doesn’t include is the rear Maxle. Titanium frame guards and rubberized chainstay protector come standard.

They say much of the weight savings comes from the refined top section and by going to a larger box section BB, which allowed thinner walls. But, inside is a continuous carbon tube through the BB shell, which means compatibility with their Biocentric 30 EBB. As such, this bike replaces both the AIR9 RDO and the One9 RDO and now works with all modern drivetrains. You could even throw a triple on there if you want.

Other than water bottle bosses, the only metal on the frame is found in the brake mounts. All frame sizes fit two water bottles. Not shown, there’s a new cable/hose routing port under the BB that eases installation…which was necessary because of the new solid BB tube. While 27.2 dropper posts are rare, the frame is stealth dropper compatible…and Di2 and Sideswing compatible, too.

Geometry numbers are based on a 100mm suspension fork (click to enlarge), but they say it’s fine with a 120mm fork, too.

It’ll be offered in CMYK and black/red color schemes. The matching wheel graphics are show only, but they may do them if demand is there. We think they should. Six complete bike builds will be offered:

NinerBikes.com