Niner 2021 Air 9 Frame (Metallic Silver/Baja Blue) (S)

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Price: $630.00


  • XS
  • S
  • M
  • L
  • XL
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The Air 9 aluminum hardtail blends the agility and efficiency of a pedal-friendly XC bike with the versatility, toughness and capability of a rowdy trail rig. Lightweight and snappy, poppy and peppy, the AIR 9 has plenty of stiffness to get you up to speed when you stomp on the pedals.
[R]evolution geometry puts the rider in the sweet, balanced spot on the bike. The roomy cockpit has a comfortable reach for short stem lengths, giving you quick handling and plenty of maneuverability to blast through rock gardens and cut hard corners. The steep 74-degree seat angle gets you centered over the BB for climbing and pairs nicely with the short 430mm chainstay length for supreme pedaling efficiency.. And of course, the slack, 68-degree head tube angle and long wheelbase contribute stability and self-confidence when you’re dropping into the steepest lines.

Build it your way with the AIR 9 frame-only option. Run it geared. Run it singlespeed. Nearly any drivetrain you can imagine is within reach, and Boost hub spacing gives you freedom for all the wheel and tire options you could want. Top it off with internal routing for a dropper post and you've made one capable bike!  This aluminum frame is ready for the best parts you can hang on it. 


  • 6061 Aluminum Frame: Hydroformed aluminum blends stiffness and comfort in a durable package. 
  • Tire Clearance: The Air 9 has clearance to run your choice of 29er or 27.5+ wheels and tires.
  • Lifetime Warranty: Ride, race, rally with confidence. Niner has you covered with warranty service, small parts, and a support team that actually answers the phone. Read more here >
  • Biocentric 30: BioCentric bottom bracket system gives you the freedom to easily go single-speed or geared. 
Frame: Hydroformed and welded 6061-T6 Aluminum
Fork: N/A
Max Front Suspension: 120mm   
Color: Silver/Baja Blue 
Available frame sizes: XS, S, M, L, XL
Seat collar size: 34.9mm 
Seat post size: 30.9mm 
Max Rear rotor size: 180mm 
Max Chainring Size: 1x max chain ring size 34T - Boost chainring recommended    
Front Deraileur Type: 34.9 side swing, front full   
Cable routing: External 
Headset size: 1.125" x 1.5" tapered integrated (campy style) head tube, Headset included (Cane Creek description: IS42/28.6 IS52/40) 
Chainring compatibility: standard 1x, 2x, and 3x systems 
Q-Factor: 168mm 
Bottom Bracket type: 73mm PF30 BB Shell (adaptors required for BSA Type BBS) (compatible with Biocentric 30BB
Brake mount type: Post mount 
Rear wheel spacing: Boost 148mm
Front wheel spacing: Boost 110mm
Max tire size: 29 x 2.4 or 27.5 x 3.0 (varies by brand, some tires may not fit)

This product was added to our catalog on November 6, 2020

Thursday, Feb 4 2021 (about a year ago)
Niner 2021 Air 9 Frame (Metallic Silver/Baja Blue) (XS)
Beautiful frame! I love the finishes. It's what I expected.
Verified Owner
Thursday, Feb 4 2021 (about a year ago)
Niner 2021 Air 9 Frame (Metallic Silver/Baja Blue) (M)
Beautiful frame! I love the finishes. It's what I expected.

Sizing Recommendations for Riders Who Fall Between Sizes:

  • Sizing down will provide a more maneuverable ride while sizing up will provide more stability
Rider Height (Feet)Rider Height (Meters)
XS5' - 5'5"1.53 - 1.65m
S5'3" - 5'9"1.6 - 1.75m
M5'8" - 6'1.73 - 1.83m
L5'11" - 6'3"1.8 - 1.91m
XL6'3" - 6'7"1.91 - 2.01m

Note: All sizing recommendations are provided by the manufacturer and may differ for each rider.


Note: Geometry chart is for 120mm of fork travel
(A) Top Tube Length570mm585mm603mm627mm652mm
(B) Seat Tube Length356mm394mm419mm483mm533mm
(C) Chainstay Length Actual430mm430mm430mm430mm430mm
(D) Horizontal Chainstay427mm427mm427mm427mm427mm
(E) Front Center678mm693mm711mm737mm764mm
(F) Wheelbase1102mm1117mm1136mm1162mm1189mm
(G) Bottom Bracket Drop52mm52mm52mm52mm52mm
(H) Headtube Length100mm100mm110mm125mm145mm
(I) Headtube Angle68.0°68.0°68.0°68.0°68.0°
(J) Seat Tube Angle74.0°74.0°74.0°74.0°74.0°
(K) Stand Over Height698mm729mm748mm800mm841mm
(L) Reach395mm410mm425mm445mm465mm
(M) Stack610610mm620mm634mm652mm
(A) Top Tube Length22.4"23.0"23.7"24.7"25.7"
(B) Seat Tube Length14.0"15.5"16.5"19.0"21.0"
(C) Chainstay Length Actual16.9"16.9"16.9"16.9"16.9"
(D) Horizontal Chainstay16.8"16.8"16.8"16.8"16.8"
(E) Front Center26.7"27.3"28.0"29.0"30.1"
(F) Wheelbase43.4"44.0"44.7"45.8"46.8"
(G) Bottom Bracket Drop2.05"2.05"2.05"2.05"2.05"
(H) Headtube Length3.9"3.9"4.3"4.9"5.7"
(I) Headtube Angle68.0°68.0°68.0°68.0°68.0°
(J) Seat Tube Angle74.0°74.0°74.0°74.0°74.0°
(K) Stand Over Height27.5"28.7"29.5"31.5"33.1"
(L) Reach115.5"16.1"16.7"17.5"18.3"
(M) Stack24.0"24.0"24.4"24.9"25.7"