The all new Niner SIR9 was developed with heavy collaboration from Reynolds to develop some unique tube shapes with their high end 853 chromoly.
The new SIR9 frame uses a custom bent 853 DZB (Double Zone Butting) downtube, something not typically done with that type of steel tubing, and mates it with a 631 44mm headtube. The latter lets you run either a modern tapered fork with the included external cup tapered headset, or use an internal headset with a straight 1-1/8″ steerer fork.
It’ll come stock with their Biocentric II bottom bracket system and is compatible with their CYA BB inserts, so you can run it singlespeed or with any geared-type bottom bracket design (PF30, BB30, PF92 and threaded external cup). The other major update is a Maxle 12×142 rear axle.
The bent downtube isn’t new in and of itself. The magic was in Reynolds’ ability to use their top end 853 steel and do it while maintaining strength. The dual butting profiles put thicker tube walls at the headtube, then thinner butting profiles elsewhere. The benefit is the lively ride and lighter weight with improved fork crown clearance. Typical straight tubes meet really high on the headtube, in many cases joining the top tube in a conjoined section. This minimizes contact with the headtube and doesn’t allow for the strongest junction. The new SIR9 gives the frame adequate separation between tubes for a stiffer, stronger front end.
The 44mm headtube first found love among handmade builders looking to offer modern tapered forks. For Niner’s steel bike fans, this lets them run their tapered-only RDO carbon fork on the new SIR9, along with any other tapered 1-1/8″ to 1.5″ forks.
The stays are custom 3D bent and shaped steel with investment cast dropouts and seat- and chainstay bridges. The shaping provides heel and tire clearance and maintains a lively ride while the 12×142 axle and strong dropouts keep it properly stiff.
The geared bikes get dropouts with a derailleur hanger…
And the singlespeed dropouts are extremely clean and minimal. Post mount brake tabs are located inside the rear triangle with a nice, bullet-shaped upper mount tucked into a bend in the seat stay.
There’s no adapter or spacer to let you run your standard 135mm QR wheels, so you’ll need to upgrade your rear hubs (or, hopefully, just put on new end caps) to 12×142.
For a size Medium, claimed painted frame weight is 2,100g (4.36lbs) without any hardware. With rear Maxle, seat collar, EBB and headset is 2,390g (5.27lbs).
LIMITED EDITION IMBA FRAMES
Want one of the new SIR9 frames? You can wait about
six 12 weeks until they start shipping, or you can bid on one of six limited edition IMBA frames and get yours much, much sooner. These custom frames are being auctioned off starting Tuesday evening, June 19, to raise money for IMBA and will ship shortly thereafter. Become a fan of Niner on Facebook to get a link as soon as the auction goes live.
The auction includes 1 small, 2 medium, 2 large and 1 XL and include matching RDO forks, as shown here.