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.... Read More