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Build Overview
This is our XC version of the custom Niner AIR 9 2-Star build. We created two configurations from the AIR 9 2-Star platform: a Trail build (covered in another post) and this lighter, snappier XC-focused version. The goal was to give riders who want a fast, efficient hardtail another strong option at a very competitive price point.
The Niner AIR 9 aluminum frame remains the foundation—simple, clean to service, and externally routed. On this XC setup, we paired it with the Fox Rhythm 32 fork in a 100 mm travel configuration. We also made cockpit tweaks, tire changes, and kept the drivetrain consistent with the 2-Star parts kit to keep the bike firmly in that sub-$1,500 category.
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Full Build Specs
- Frame: Niner AIR 9 (aluminum, 148 boost spacing)
- Cable Routing: Fully external brake + shift housing
- Dropper Ready: Yes (external entry, internal routing)
- Fork: Fox Rhythm 32, 100 mm travel, boost, thru axle
- Drivetrain: Niner 2-Star build kit (SRAM SX crank, SRAM SX derailleur, NX 11–50T cassette)
- Brakes: SRAM Level (2-piston calipers)
- Wheelset: Stock Niner house-brand XC wheels
- Tires: Vittoria Barzo (front) + Vittoria Mezcal (rear), 2.35 width
- Cockpit: Ritchey Comp (XC bar), longer stem for XC fit
- Seatpost: Standard aluminum post
- Saddle & Grips: Niner house-brand components
Build Notes
The AIR 9 aluminum frame keeps everything simple: full external routing along the back of the frame, boost spacing, thru-axles, and room for a dropper post through an internal port if a rider wants to install one. We intentionally left the dropper off to keep the price down and avoid putting a cheap unit on a bike that deserves better.
The biggest change from the stock 2-Star AIR 9 is the fork. Niner had a run of AIR 9 frames paired with Fox Rhythm 32 forks in a 100 mm configuration, so we grabbed those specifically for XC builds. This fork is lighter and more responsive than the Marzocchi Z2 used on the Trail build, giving this version a distinctly XC feel.
We kept the stock Niner wheels—they’re the same wheels Niner uses across many of their 2-Star XC builds, including the RKT. For tires, we went with our shop-favorite XC combo: Vittoria Barzo up front for cornering confidence and a Vittoria Mezcal in the rear for speed and low rolling resistance.
For cockpit changes, we swapped the short stem and riser bar for a Ritchey Comp XC bar and a slightly longer stem. This works better with the 100 mm fork and positions the rider in a more efficient XC posture.
This build fits riders looking for a fast, simple bike to ride local singletrack without getting into overly aggressive terrain. It’s lightweight for an aluminum frame, very competitive at its price point, and offers riders multiple ways to configure it if they want to upgrade wheels, drivetrain, or cockpit later on.
Between this XC version and the Trail version, we feel like we’ve created two solid options in the sub-$1,500 category that outperform the big-brand offerings in the same price range.
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Work With Us On a Custom Build
If you’re considering a custom XC or trail hardtail, we can build one to fit your riding style and budget.