By Josh Patterson
Last year about this time Niner Bikes unveiled its first carbon full suspension platform, the Jet 9 RDO (read our review in issue #163). This year Niner took time to reinvest in one of the first frames in its line-up, the geared and singlespeed-compatible S.I.R. 9. The company felt steel bikes were being equated with retro, which seemed unfair to such a versatile frame material.
“Steel was being left behind,” said company founder Chris Sugai. "You couldn’t run tapered forks, you couldn’t run Maxles.” Niner’s goal was to revise the frame to make it compatible with current standards while maintaining the S.I.R. 9’s soulful ride quality.
The two most visible changes include the use of a larger diameter, 44mm head tube, which will allow riders to run straight or tapered steerers on their forks, and a 142×12 Maxle rear end to bolster stiffness and make it compatible with the latest hubs and wheelsets.
Other, more subtle changes include switching the rear brake mount from IS to post-mount, and moving it from the seatstay to the chainstay. Not only does this change give the rear end a much cleaner look, it also does away with the need for a brace between the seat- and chainstays, and allows for the use of thinner-walled seatstays to improve the ride quality.
Niner also redesigned its eccentric bottom bracket. Dubbed Biocentric II, the new unit uses two 6mm bolts, versus a single 8mm used previously, to more evenly distribute clamping forces and lessen the chance the unit will creak. There’s also a keyed 8mm slot to make chain tension adjustments. The Biocentric II is also compatible with Niner’s CYA modular bottom bracket system, allowing riders to choose the bottom bracket technology that best fits their needs: BB30, PressFit 30, BB92, or a tried-and-true threaded system. Best of all, Biocentric II is backwards compatible with Niner frames that use the Biocentric I EBB. Pricing and availability are not set.
Niner will also be offering their Maxle hardware to custom frame builders.
The Reynolds 853 front triangle was redesigned to accommodate the larger diameter headtube. Niner worked with Reynolds to select the right butting profile to ensure the frame would pass stringent EN testing requirements.
While the S.I.R. 9 receives numerous updates the frame’s geometry remains unchanged.
Colors will be Tamale Red (with an option to purchase the frame with a color-matched RockShox XX SID fork), and Arctic White. Weight for a medium S.I.R. 9 frame with Maxle hardware and seatpost clamp is approximately 4.8 pounds. It will retail for $999 and will be available in approximately 12 weeks.
On the trail
As mentioned previously, the updated S.I.R. 9 has geometry that is identical to its predecessor—quick, but not twitchy is how I would describe it. The frame is designed around 80-100mm forks. My demo bikes was spec’d with a 100mm RockShock SID fork and a mostly XTR drivetrain, all of which worked well enough that I could focus all of my attention on the frame.
I was curious to find out of the inclusion of modern features, designed to bolster frame stiffness, might exaggerate the steel frame’s lively feel to the point that “complaint” turned into “flexy.”
I’m happy to report that this was not my impression. Through tight switchbacks, bermed turns, and the occasional blast through rocky chunder the S.I.R. 9 displayed the refined ride quality one would expect from a high-end steel frame: comfortable, lively and precise.
So I mentioned the S.I.R. 9 will not be available for 12 weeks, and that it comes in red or white. Well, there is a loophole. Think this is the right bike for you? Want to help IMBA fight the good fight? Well, there’s a way to do both at the same time.
Niner is auctioning off on eBay six custom-painted, IMBA-themed S.I.R. 9 frames with matching carbon RDO forks—seen here with the yellow paint. One hundred percent of the proceed go directly to IMBA. The auctions end June 29, so bid early and often!