SIR 9

Steel is real - Made from Reynolds 853 steel and a 120mm fork for all-day epics, multi-day missions, and backcountry exploration.

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

"New trends in geometry and componentry are inspiring some really fun bikes, even for those who don't consider themselves the hardtail type."

"Niner has just released the latest drool-worthy steel hardtail with a bikepacking predisposition."

"It's still steel and 29in, but the new SIR 9 from Niner has a whole load more versatility built into it."

"The latest SIR 9 is an attractive option for riders who want a classic material in an up-to-date, versatile package."

More Information
Available Frame SizesSM, MD, LG, XL
Available ColorsBlack/Bronze
FrameHAND WELDED AIR HARDENED REYNOLDS 853 STEEL; EXTERNAL CABLE ROUTING; INTEGRATED BOTTLE, BAG, RACK AND FENDER MOUNTS; 12X148 THRU AXLE
ForkFOX 34 SC FLOAT FACTORY EVOL FIT4, 3 POSITION W/ ADJ, KASHIMA COAT, 120MM, 110X15MM, 44MM OFFSET
ShockN/A
Front WheelSTANS FLOW S1 NEO CL
Rear WheelSTANS FLOW S1 NEO CL
Front TireSCHWALBE NOBBY NIC EVO SUPER TRAIL TLE ADDIX SPEEDGRIP 2.6
Rear TireSCHWALBE NOBBY NIC EVO SUPER TRAIL TLE ADDIX SPEEDGRIP 2.35
BrakesSRAM G2 R
Brake LeversSRAM G2 R
Brake Rotors180/160 CENTERLINE ROTORS
ChainSRAM GX EAGLE 12SP
Front ShifterN/A
Rear ShifterSRAM GX EAGLE 12SP
Front DerailleurN/A
Rear DerailleurSRAM GX EAGLE 12SP
CassetteSRAM EAGLE XG 1275, 10-52T
CranksetSRAM DESCENDANT 7K EAGLE DUB, 32T (S/M/L - 170MM, XL - 175MM)
Bottom BracketSRAM DUB PF30
SaddleNINER CUSTOM WITH CR-MO RAILS, EMBOSSED NINER GRAPHIC
SeatpostKS LEV SI (XS/S-100MM, M/L/XL-150MM)
HandlebarRACE FACE AEFFECT R 780MM WIDE, 20MM RISE, 35MM CLAMP
StemRACE FACE AEFFECT R 40MM, 35MM CLAMP
HeadsetNINER INTERNAL ZS SHIS DESCRIPTION ZS44/28.6|ZS56/40
GripsNINER GRRRIPS L/O NYLON SOFT COMPOUND
Tech Specs
frame mounts and fittings2 Inner Triangle Bottle Mounts, 1 Mount Under Down Tube, 1 on top tube, rack and fender mounts.Rear suspension traveln/a
Maximum front suspension120mmFork offset44mm
Shock sizen/aShock mounting hardware
n/a
Suggested shock sagn/aSeatpost size30.9mm
Seat collar size34.9mmCable routingexternal
Front derailleur type34.9 side swing, front pullHeadset size1.125" X 1.5" Tapered Zero Stack Head Tube, 44mm Upper, 56mm Lower, Cane Creek Description: ZS44/28.6 ZS56/40
Pivot bearing specsn/aChainring compatibilityCompatible With Standard 1X, 2X And 3X Systems
Maximum chainring size1x max chain ring size: 36T - Boost Chainring RecommendedQ-Factor168mm
ISCG compatibilitynoBottom bracket type73mm PF30 BB Shell (Adapters Required For BSA Type BBs); compatible with Biocentric 30 BB
Brake mount typePost mountMaximum rear rotor size180mm
Rear wheel spacingBoost 12x148mmRear wheel through-axle specM12x1.75Px182L
Front wheel axle spacingBoost 15x110mmFront wheel through-axle spec
Max tire size29x2.4 or 27.5x3.0 Tire (Tire Sizes Vary By Brand, Some Tires May Not Fit)
Geometry
Geometry Chart
(A) TT Length (B) Seat Tube Length (C) Chainstay Length Actual (D) Horizontal Chainstay (E) Front Center (F) Wheelbase (G) BB Drop (H) Headtube Length (I) Headtube Angle (J) Seattube Angle (K) Standover Height (L) Reach (M) Stack
Metric
Fork Travel (MM) 120 120 120 120 120 120 120 120 120 120 120 120 120
SM 595 396 430 427 693 1118 52.0 100 68.0 74.0 721 410 611
MD 603 421 430 427 711 1136 52.0 110 68.0 74.0 739 425 620
LG 627 485 430 427 737 1162 52.0 125 68.0 74.0 791 445 634
XL 652 533 430 427 764 1189 52.0 145 68.0 74.0 830 465 652
Imperial
Fork Travel (MM) 120 120 120 120 120 120 120 120 120 120 120 120 120
SM 23.4 15.6 16.9 16.8 27.3 44.0 2.0 3.9 68.0 74.0 28.4 16.1 24.0
MD 23.7 16.6 16.9 16.8 28.0 44.7 2.0 4.3 68.0 74.0 29.1 16.7 24.4
LG 24.7 19.1 16.9 16.8 29.0 45.7 2.0 4.9 68.0 74.0 31.1 17.5 24.9
XL 25.7 21.0 16.9 16.8 30.1 46.8 2.0 5.7 68.0 74.0 32.7 18.3 25.7
Sizing

Frame Size Recommendations by Height

X-SM

5'0"–5'5"
1.53–1.65M

SM

5'3"–5'9"
1.6–1.75M

MED

5'8"–6'0"
1.73–1.83M

LG

5'11"–6'3"
1.8–1.91M

X-LG

6'3"–6'7"
1.91–2.01M

Inseam Sizing

Bike inseam sizing example chart

For riders who fall between sizes, we recommend sizing down for a more maneuverable ride or sizing up for more stability.