Niner Air 9 Carbon Frame

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The Niner Air 9 frame is a lovely thing to look at; all swoopy lines and elegant curves. Even the headbadge seems to exude speed. NinerAir9C007006 Removing the frame from the box, it was nice to see a headset included (with Niner branded spacers) along with a Maxle and a variety of different rubber stops and bungs for internal routing, or blanking off if that’s your preference. The underside of the downtube is protected by a large area of helicopter tape to ensure that rock dings don’t ruin your day (or your finish), and any chain-suck issues are headed off with a couple of titanium plates to protect that fragile carbon. Bottle bosses are finished off with lovely anodised bolts (also Niner branded), and the internal routing is pre-lined to ease any cabling woes you may have.

Wot it says
Wot it says

The Air 9 has enormous main tubes, including the downtube, which is a stiffness-enhancing hexagonal shape. They all blend into one another beautifully, and lend it an almost organic air. Despite its obvious XC leanings, Niner have made a frame that is as comfortable on the trail as the race course – there’s a 142×12 Maxle back end, clearance for 2.4in tyres, internal routing for a dropper post, and the frame is perfectly comfy taking a 120mm fork.

Praxis BB insert was creak-free throughout - but somewhat fond of the frame...
Praxis BB insert was creak-free throughout – but somewhat fond of the frame…

The BB shell is Niner’s CYA, which basically means it’s a whopping great hole, into which you press-fit the adaptor of your choice. I went with a Praxis PF30 to Shimano adaptor, which pressed in with a headset press and provided creak-free performance throughout the test period. One caveat with this, though, is that tolerances here are tight – so the collar provided with the BB remained permanently in place. Great for creak-free performance, but slightly less great for getting the collar out again…

Beautiful dropouts - and XTR
Beautiful dropouts – and XTR

So we built up our test frame with some seriously high-end kit, including a full 2015 XTR Race cable groupset, XTR wheels and BOS Dizzy 120mm fork: even on our XL frame, with a dropper post and some full-on Specialized Purgatory trail rubber the bike weighed in at a mere whisker over 24lbs.

I used some of the internal routing for the dropper post (the routing in the down tube) for the new XTR side-pull front mech, which worked perfectly, although naturally it becomes difficult to run an internal dropper post (there’s also no provision on the outside of the frame for an external dropper). It’s potentially quite feasible to route it around the BB shell, but I didn’t try. And of course, if you’re gram-counting you won’t be running a dropper in any case.

There’s internal routing for gearing, then, but not for the brake hose, which still runs along the bottom of the toptube and down the seat stay. Full internal routing would perhaps look tidier, but may potentially create issues getting hoses around that bottom bracket.

Dropper-post routing
Dropper-post routing

So, all the bling, then, in a rufty-tufty sort of way. That’s some trail weapon. The Air 9 uses Niner’s race geometry, so it’s blessed with very short chainstays to keep things tucked in at the back, and out XL frame has a rangy 25.5in top-tube, which keeps things relatively long and low at the front. Couple this to a 70º head angle (with a 120mm fork – it’s 71º with a 100mm) and you’ve got yourself a rip-snorting charger…

Trail Notes

… and so it proved to be. It’s hard to be slow, riding a frame like this – even with the short stem and wide bars combo. I found it extremely easy to balance – it was as simple to loft the back as the front. The geometry felt a little twitchy when things got steep to be sure (I was glad I fitted a dropper post), but similarly it provided a great response when things became properly fast – and the bike proved hugely rewarding when things got twisty, too. Point and shoot indeed. NinerAir9C002001 Carve round that corner, click down the block a couple and stomp on the pedals: whoosh. Climbing was as easy as you’d predict, too. The front remained well planted and things rarely became wandery, but it’s on swoopy, twisty singletrack where I really felt the Niner show its true colours. Getting up to speed was emphatically not a problem; nor was maintaining it.

Kink through that little chicane as if it wasn’t there; slightly weight the front end, outside pedal down and track beautifully through the corner – all at lightning speeds, but you’re completely in control. It’s one of those great bike that makes you feel you’re not riding at all; you’re just hovering at 30mph above the trail.

Heel scuff could've been avoided with helicopter tape
Heel scuff could’ve been avoided with helicopter tape

Issues? I did notice some heel-rub on the chainstays, where they flare out at the dropouts, which isn’t ideal – but this could easily be remedied by the judicious use of helicopter tape. Apart from that, this is a very hard frame to fault.

Ti frame protection
Ti frame protection

Overall: If you want a state-of-the-art, light as anything 29er XC hardtail which is also at home on the trails, then this is it. There may be others as good, but it’s unlikely you’ll find much better. Recommended.

Review Info

Product:Air 9 Carbon
From:Jungle -
Tested:by Barney for

Comments (0)

    I know I’m slightly obsessed with chainstay length on 29ers (having ridden Canfield, 2 Souls etc and seen the light) but “it’s blessed with very short chainstays” – no it’s not. 439mm is average at best.

    Excellent…another thing to want! That’ll help keep my mind off reality!

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