This SIR 9 XT Bicycle is an Excel Sports built single-speed with Niner's sweet steel SIR 9 frame and tapered carbon fork. Steel is a perfect hardtail frame material for single-speed riding due to it's resilient compliance that smooths out ride. Mountain bikers who have experienced single-speed riding on a 29er understand the essence of the wheel platform, and riding rigid does offer a sense of purpose, rhythm, and simplicity that is hard to beat. Every trail rider owes it to his or her self to have a single-speed hardtail in their garage. It never surprises us when we hear "It's my favorite bike! I ride it all the time."

The blend of premium Reynolds steel tubes, Niner geometry, and the speed and control of the 29er platform is inspiring to old school steel proponents who still enjoy the advances of modern technology. So what makes it so desirable? Lightweight resilient tubes and shapes still offer the sensational ride quality, but are more responsive, with greater strength. Niner taps into the world of steel through Reynolds, perhaps the best known bicycle steel manufacturer of our lifetime. The SIR features the legendary 853 blend, with Double Zone Butting, for the oversized downtube. DZB allows the builder to define localized shapes and strength that complement the tandem requirements of the downtube. You get the stiffness at the headtube and the bottom bracket you need, while the butting of the central zone delivers essential compliance. The top tube and seattube are also 853. For the 44mm oversized headtube, Niner chose the 631 blend, which is heavier, but inherently stronger and holds large-miter interface welds perfectly. By opting for a pure 44mm headtube, Niner allows riders to choose tapered steerer or straight (even 1⅛ with a reducing headset). The short 631 cylinder will defeat torque and provide essential stability under any terrain or load.

The rear triangle employs s-bend stays and curves that not only transfer power, but offer compliance without ever feeling soft or squishy. When you put down the pedal power, the SIR 9 jumps to attention. Interestingly, Niner built the rear disc mount as a post mount within the triangle, which is common with carbon and aluminum, but not with steel. Investment cast drop-outs and bridges add strong connective junctions. The 12/142mm Maxle thru-axle system and rear triangle assembly delivers perfect wheel tracking and power transfer while accommodating most tires up to 2.4" width. Power comes through the oversized bottom bracket shell. Niner packages the SIR 9 frame with their 73mm wide BioCentric II bottom bracket, which allows for 8.5mm off center adjustment- or more than most eccentric options- for easy single-speed set-up and adjustment. Bio-Centric II requires external threaded BB models. Should you decide to change a 1x or 2x geared drivetrain, you just need to get buy the derailleur hanger and a Niner CYA adapter for whatever crank/BB interface you decide to run.

The geometry has been optimized for a 100mm fork, and here the rigid Niner Carbon Fork truly shines. It rides like a dream on the trail and can easily accommodate tires up to 2.4". The 440mm chainstays feel shorter and quicker, especially with the 70.3° headtube angle. Stable, quick, and responsive, the bike feels light, with great back end control, and the lightweight fork keeps the front end agile when you need to be nimble through technical rock gardens. Overall, the bike tracks exceptionally well, completely maximizing the 29er size wheels.

The kit starts with NoTubes ZTR Rapid SS thru-axle wheelset. The tubeless ready rims are very close in shape to the Crest model, but wider, at 25mm outside (21mm internal), making them ideal for carrying wider tires at low to mid pressures. The alloy hubs use a 6-bolt interface, and the rear has a SS specific freehub. The Surly 18T BMX steel cog is famous for it's long wear. The crankset is a 175mm long XT M8000 with a 30T 1x chainring. The MT800 threaded bottom bracket carries the Hollowtech II 24mm spindle. The XT theme continues with the hydraulic disc brakes. Favorites of trail riders everywhere, these brakes are powerful, consistent, and easy to service. The RT86 IceTech six bolt rotors complete the braking system.

Ritchey supplies the Blatte color cockpit, featuring a singe bolt alloy 27.2/350mm seatpost carrying a WCS V3 Streem saddle, a 200 gram beauty that offers a good fit for many riders, and exploits alloy ti rails for rider comfort. The stem is a 90mm WCS C220, perfect for carrying a wide handlebar. We chose the 720mm Ritchey Comp alloy bar for three reasons. First, it does the job. Second, it is inexpensive, and third we find that bars, along with saddles, are the first items that riders replace to suit their preferences. For grips the ESI Chunky in black are very popular and super comfortable on the trail. Niner supplies the tapered headset, a Cane Creek ZS44/28.6, EC44/40 headset for 1⅛" to 1.5". And that is it.

Single-speed riding, especially on a rigid bike, can completely retrain you as a trail rider. Gearing and suspension is great- but limits the rider and bike handling skills, especially on XC trail. You can learn, or re-learn handling skills, cornering, and bike manipulation that will actually improve your entire skill set. This Niner SIR 9 XT Single-Speed bike could change your perspective as a rider. All you need is a set of pedals and you are ready to go. Enjoy the thrill and feel of high quality steel and the simplicity of single-speed, rigid riding with Niner.