

Made from metal
SIR 9: rugged, reliable, comfortable Reynolds 853 steel
There’s a new bike in town. It’s built to last and not let you down. When you’re spinning up the steeps, bombing down the backcountry and grinding out the final miles as the sun sinks into the horizon, you need a bike you can trust. A comfortable, capable, hand-built bike made from proven, air-hardened, heat-treated steel. That’s right, steel. Because Steel Is Real and it’s fully optimized in the SIR 9.

Yes, SIR
So what’s the story with our steel hardtail? For starters, it’s STEEL. This classic metal alloy from materials icon Reynolds gives us the comfortable, durable, capable, versatile, “ride it hard and put it away wet” frame that we have always wanted.
To make it even more tasty, the SIR 9 is strapped with a 120mm travel FOX suspension fork, perforated with no fewer than 18 threaded, reinforced mounting points, clears 29x2.4” (or 27.5x3.0”) tires, and offers easy options for geared or singlespeed drivetrains. No excuses - pack an extra jacket and a PBR, go farther, and stay out longer.
The SIR 9 is perfect for just about any type of riding, no matter how long or short. It’s a butt-kicking, grin-inducing lunch ride launch pad when you only have 30 minutes to burn in the back lot. It’s also made for multi-day missions in the backcountry. And it’s made to make you happy the minute you throw a leg over it.

Get real with Reynolds 853 steel
This modern metal alloy is well known for its unique properties. It actually strengthens in the tube junctions when it air-cools after welding. So, we can do more with it, yet we actually can use less material. For instance, we can design intricate chainstay and seat-stay yokes to accommodate either 29” or 27.5-Plus wheels and tires, with plenty of mud clearance to spare. We also don’t need to add heavy gussets and tube reinforcements - it’s plenty strong as-is.

“Trail country” geometry
Blurring the lines between modern trail bike geometry and traditional cross-country geometry, the SIR 9 occupies a niche we lovingly call “trail country.” If you’re doing a combination of long pedaling rides, stiff climbs, extended descents, and spicy technical sections, you’ll love what we’ve done here. “Trail country” geometry translates to modern trail manners when you need them most, with no sacrifice of efficiency or agility.
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.
Pack it up, pack it in, let me begin...
The versatility of steel gives us the option to add accessory mounting points, and boy did we ever. There are rack and fender mounts, bottle cage mounts, frame bag mounts, and even a top-tube bento box mount. The rear rack mounts are strong enough to hold 55lbs.


Reynolds 853 steel
The magic air-hardened metal from Reynolds actually strengthens after welding. Read More
Multiple mounting options
No fewer than 18 mounting points give you the freedom to run racks, fenders, bottles, frame bags, a bento box, and more. Read More
Biocentric 30
Do you yearn for simplicity? Our patented BioCentric bottom bracket system gives you the freedom to easily go single-speed or geared. Read More
Trail ready geometry
With a longer top tube and slacker head tube angle, the SIR 9 is stable, trail-specced and ready to get shreddy in all circumstances.
Integrated dropper post routing
Clean and concealed, SIR 9 is ready with ports on the seat tube for internal dropper post cable routing.
Lifetime warranty
Ride, race, rally. We have you covered with warranty service, small parts, and a support team that actually answers the phone. Read More
Tire clearance
Need room to roam? We got it. The SIR 9 has clearance to run your choice of 29er or 27.5+ wheels and tires.Specifications
Our premium, 5-Star SRAM X01 Eagle build kit and the reliable SIR 9 frame will give you smiles for miles. With 120mm of premium FOX front suspension and DT Swiss XMC 1501 SPLINE wheels, riding so far and so hard was never so easy.
- DT Swiss XMC 1501 SPLINE 30 carbon wheels
- FOX 34 SC Float Factory EVOL FIT 4 fork w/Kashima coat, 120mm travel
- KS LEV SI dropper post
Available frame sizes | SM, MD, LG, XL | Available colors | CEMENT GRAY/BLACK |
Frame | HAND WELDED AIR HARDENED REYNOLDS 853 STEEL; EXTERNAL CABLE ROUTING; INTEGRATED BOTTLE, BAG, RACK AND FENDER MOUNTS; 12X148 THRU AXLE | Fork | FOX 34 SC FLOAT FACTORY EVOL FIT4, 3 POSITION W/ ADJ, KASHIMA COAT, 120MM, 110X15MM, 44MM OFFSET |
Shock | N/A | Tubes / Sealant | STANS NO TUBES SEALANT (2 X 2oz BOTTLES) |
Front wheel | DT SWISS XMC 1501 SPLINE 30, CENTERLOCK, 110X15MM | Rear wheel | DT SWISS XMC 1501 SPLINE 30, CENTERLOCK, 148X12MM, RATCHET EXP 36 |
Front Tire | SCHWALBE NOBBY NIC EVO SUPER TRAIL TLE ADDIX SPEEDGRIP 2.6 | Rear tire | SCHWALBE NOBBY NIC EVO SUPER TRAIL TLE ADDIX SPEEDGRIP 2.35 |
Brakes | SRAM G2 RSC | Brake levers | SRAM G2 RSC |
Brake rotors | 180/160 CENTERLINE X ROTORS | Chain | SRAM X01 EAGLE 12SP |
Front shifter | N/A | Rear shifter | SRAM X01 EAGLE 12SP |
Front derailleur | N/A | Rear derailleur | SRAM X01 EAGLE 12SP |
Cassette | SRAM EAGLE XG 1295, 10-52T | Crankset | SRAM X1 EAGLE CARBON DUB 32T CNC RING |
Bottom bracket | SRAM DUB PF30 | Saddle | NINER CUSTOM TR WITH CRN-TI RAILS, PRINTED NINER GRAPHIC |
Seatpost | KS LEV SI (XS/S-100MM, M/L/XL-150MM) | Handlebar | RACE FACE NEXT R 800MM WIDE, 35MM RISE, 35MM CLAMP |
Stem | RACE FACE TURBINE R 40MM, 35MM CLAMP | Headset | NINER INTERNAL ZS SHIS DESCRIPTION ZS44/28.6|ZS56/40 |
Grips | NINER GRRRIPS L/O SOFT COMPOUND | Approximate weight |
This 4-Star SIR 9 is dressed for success with a light, stiff FOX 34 120mm travel suspension fork, Shimano XT drivetrain, and DT Swiss M1700 wheels. No excuses - get out and ride!
- DT Swiss M1700 wheels
- FOX 34 SC Float Factory EVOL FIT 4 fork w/Kashima coat, 120mm travel
- KS LEV SI dropper post
Available frame sizes | SM, MD, LG, XL | Available colors | CEMENT GRAY/BLACK |
Frame | HAND WELDED REYNOLDS 853 STEEL; EXTERNAL CABLE ROUTING; INTEGRATED BOTTLE, BAG, RACK AND FENDER MOUNTS; 12X148 THRU AXLE | Fork | FOX 34 SC FLOAT FACTORY EVOL FIT4, 3 POSITION W/ ADJ, KASHIMA COAT, 120MM, 110X15MM, 44MM OFFSET |
Shock | N/A | Tubes / Sealant | STANS NO TUBES SEALANT (2 X 2oz BOTTLES) |
Front wheel | DT SWISS XM 1700 SPLINE 30, CENTERLOCK 110X15MM | Rear wheel | DT SWISS XM 1700 SPLINE 30, CENTERLOCK 148X12MM |
Front Tire | SCHWALBE NOBBY NIC EVO SUPER TRAIL TLE ADDIX SPEEDGRIP 2.6 | Rear tire | SCHWALBE NOBBY NIC EVO SUPER TRAIL TLE ADDIX SPEEDGRIP 2.35 |
Brakes | SHIMANO XT M8100, METAL PAD W/ FIN | Brake levers | SHIMANO XT M8100 |
Brake rotors | 180/160 MT800 ROTORS | Chain | SHIMANO XT M8100 W/ QUICKLINK |
Front shifter | N/A | Rear shifter | SHIMANO XT M8100 12SP I-SPEC EV |
Front derailleur | N/A | Rear derailleur | SHIMANO XT M8100 SGS 12SP |
Cassette | SHIMANO XT M8100 12SP, 10-51T | Crankset | RACEFACE NEXT R CARBON 12SP, 32T |
Bottom bracket | RACEFACE PF30 | Saddle | NINER CUSTOM TR WITH CRN-TI RAILS, PRINTED NINER GRAPHIC |
Seatpost | KS LEV SI (XS/S-100MM, M/L/XL-150MM) | Handlebar | RACE FACE NEXT R 800MM WIDE, 35MM RISE, 35MM CLAMP |
Stem | RACE FACE TURBINE R 40MM, 35MM CLAMP | Headset | NINER INTERNAL ZS SHIS DESCRIPTION ZS44/28.6|ZS56/40 |
Grips | NINER GRRRIPS L/O SOFT COMPOUND | Approximate weight | 27.7 lbs |
Expect the best from our fan favorite 3-Star SRAM GX Eagle kit. Mated to the SIR 9 frame and FOX 34 Float Factory suspension, every feature of this adventure-seeking singletrack slayer is fully optimized.
- DT Swiss M 1900 SPLINE wheels
- FOX 34 SC Float Factory EVOL FIT4, 3 position, 120mm, 110X15mm, 44mm offset
- KS LEV SI dropper post
Available frame sizes | SM, MD, LG, XL | Available colors | CEMENT GRAY/BLACK |
Frame | HAND WELDED REYNOLDS 853 STEEL; EXTERNAL CABLE ROUTING; INTEGRATED BOTTLE, BAG, RACK AND FENDER MOUNTS; 12X148 THRU AXLE | Fork | FOX 34 SC FLOAT FACTORY EVOL FIT4, 3 POSITION W/ ADJ, KASHIMA COAT, 120MM, 110X15MM, 44MM OFFSET |
Shock | N/A | Tubes / Sealant | STANS NO TUBES SEALANT (2 X 2oz BOTTLES) |
Front wheel | DT SWISS M 1900 SPLINE 30, CENTERLOCK, 110X15MM* | Rear wheel | DT SWISS M 1900 SPLINE 30, CENTERLOCK 148X12MM* |
Front Tire | SCHWALBE NOBBY NIC EVO SUPER TRAIL TLE ADDIX SPEEDGRIP 2.6 | Rear tire | SCHWALBE NOBBY NIC EVO SUPER TRAIL TLE ADDIX SPEEDGRIP 2.35 |
Brakes | SRAM G2 R | Brake levers | SRAM G2 R |
Brake rotors | 180/160MM SRAM CENTERLINE X | Chain | SRAM GX EAGLE 12 SP |
Front shifter | N/A | Rear shifter | SRAM GX EAGLE 12 SP |
Front derailleur | N/A | Rear derailleur | SRAM GX EAGLE 12 SP |
Cassette | SRAM EAGLE XG 1275, 10-52T | Crankset | SRAM DESCENDANT 7K EAGLE DUB, 32T |
Bottom bracket | SRAM DUB PF30 | Saddle | NINER CUSTOM WITH CrMo RAILS, EMBOSSED NINER GRAPHIC |
Seatpost | KS LEV SI (XS/S-100MM, M/L/XL-150MM) | Handlebar | RACE FACE AEFFECT R 780MM WIDE, 20MM RISE, 35MM CLAMP |
Stem | RACE FACE AEFFECT R 40MM, 35MM CLAMP | Headset | NINER INTERNAL ZS SHIS DESCRIPTION ZS44/28.6|ZS56/40 |
Grips | NINER GRRRIPS L/O NYLON SOFT COMPOUND | Approximate weight |
Seeking simplicity, silence, and a single speed drivetrain? Look no further than our 3-Star Shimano XT single speed build. Mated to our SIR 9 frame and FOX suspension, your single-speed adventures are ready and waiting.
- Niner alloy wheels, 30mm internal width
- Shimano SLX cranks and Niner Cogalicious cog
- KS Lev SI dropper post
Available frame sizes | SM, MD, LG, XL | Available colors | CEMENT GRAY/BLACK |
Frame | HAND WELDED REYNOLDS 853 STEEL; EXTERNAL CABLE ROUTING; INTEGRATED BOTTLE, BAG, RACK AND FENDER MOUNTS; 12X148 THRU AXLE | Fork | FOX 34 FLOAT FACTORY EVOL FIT 4, 3 POSITION W/ADJ, KASHIMA COAT, 120MM, 110X44MM OFFSET |
Shock | N/A | Tubes / Sealant | STANS NO TUBES SEALANT (2 X 2oz BOTTLES) |
Front wheel | NINER ALLOY, 30MM INTERNAL WIDTH, 110X15MM | Rear wheel | NINER ALLOY, 30MM INTERNAL WIDTH, 148X12MM |
Front Tire | SCHWALBE NOBBY NIC EVO SUPER TRAIL TLE ADDIX SPEEDGRIP 2.6 | Rear tire | SCHWALBE NOBBY NIC EVO SUPER TRAIL TLE ADDIX SPEEDGRIP 2.35 |
Brakes | SHIMANO XT M8100, METAL PAD W/FIN | Brake levers | SHIMANO XT M8100 |
Brake rotors | 180/160 XT RT86 | Chain | SRAM 1 SP |
Front shifter | N/A | Rear shifter | N/A |
Front derailleur | N/A | Rear derailleur | N/A |
Cassette | NINER COGALICIOUS 20T | Crankset | SHIMANO SLX M7000, 32 T |
Bottom bracket | NINER BIOCENTRIC 30 | Saddle | NINER CUSTOM TR WITH CrMo RAILS, EMBOSSED NINER GRAPHIC |
Seatpost | KS LEV SI | Handlebar | RACE FACE NEXT R 800MM WIDE, 20MM RISE, 35MM CLAMP |
Stem | RACE FACE TURBINE R 40MM, 35MM CLAMP | Headset | NINER INTERNAL ZS SHIS DESCRIPTION ZS44/28.6|ZS56/40 |
Grips | NINER GRRRIPS L/O SOFT COMPOUND | Approximate weight | 28.8 lbs |
SRAM does it again with this 2-Star SX Eagle parts kit. It's a wallet friendly, yet high-performing parts kit. Mated to our SIR 9 frame and Marzocchi suspension, every feature of this adventure-seeking singletrack slayer is fully optimized.
- Niner alloy wheels, 30mm internal width
- Marzocchi Bomber Z2 rail suspension fork, 120mm travel
- Niner Alloy seatpost
Available frame sizes | SM, MD, LG, XL | Available colors | CEMENT GRAY/BLACK |
Frame | HAND WELDED REYNOLDS 853 STEEL; EXTERNAL CABLE ROUTING; INTEGRATED BOTTLE, BAG, RACK AND FENDER MOUNTS; 12X148 THRU AXLE | Fork | MARZOCCHI BOMBER Z2 RAIL, SWEEP ADJ, 120MM, 110X15MM, 44MM OFFSET |
Shock | N/A | Tubes / Sealant | STANS NO TUBES SEALANT (2 X 2oz BOTTLES) |
Front wheel | NINER ALLOY, 30MM INTERNAL WIDTH, 110X15MM | Rear wheel | NINER ALLOY, 30MM INTERNAL WIDTH, 148X12MM |
Front Tire | SCHWALBE NOBBY NIC EVO SUPER TRAIL TLE ADDIX SPEEDGRIP 2.6 | Rear tire | SCHWALBE NOBBY NIC EVO SUPER TRAIL TLE ADDIX SPEEDGRIP 2.35 |
Brakes | SRAM LEVEL | Brake levers | SRAM LEVEL |
Brake rotors | SRAM LEVEL | Chain | SRAM SX EAGLE 12SP |
Front shifter | N/A | Rear shifter | SRAM SX EAGLE 12SP |
Front derailleur | N/A | Rear derailleur | SRAM SX EAGLE 12SP |
Cassette | SRAM PG 1210 11-50T | Crankset | SRAM X1 1K EAGLE DUB, 32T |
Bottom bracket | SRAM DUB PF30 | Saddle | NINER CUSTOM TR WITH CrMo RAILS, EMBOSSED NINER GRAPHIC |
Seatpost | Niner alloy, 370MM | Handlebar | RACE FACE AEFFECT R 780MM WIDE, 20MM RISE, 35MM CLAMP |
Stem | RACE FACE AEFFECT R 40MM, 35MM CLAMP | Headset | NINER INTERNAL ZS SHIS DESCRIPTION ZS44/28.6|ZS56/40 |
Grips | NINER GRRRIPS L/O NYLON SOFT COMPOUND | Approximate weight | 28.8 lbs |
Available frame sizes | SM, MD, LG, XL | Available colors | CEMENT GRAY/BLACK |
Frame | HAND WELDED REYNOLDS 853 STEEL; EXTERNAL CABLE ROUTING; INTEGRATED BOTTLE, BAG, RACK AND FENDER MOUNTS; 12X148 THRU AXLE |
We make every effort to publish accurate build specs, however Niner Bikes reserves the right to make substitutions or changes to bike assembly specification at any time without notice or warning. Product images may not reflect actual specification. Minor variance in color may be visible including fork decal color. Published approximate weights are for size medium (53cm) and may vary by +/- 5% due to manufacturing tolerances.
*3-Star build wheels are subject to temporary substitution with STANS FLOW S1, ALUMINUM CLINCHER, 29MM INTERNAL, STANS NEO CL HUBS