Niner

SIR 9 Frame - Clearance

The SIR 9 has long been a favorite here, both for it's smooth, compliant ride and the wonderful versatility of being able to run it geared or singlespeed with ease. Now, the famous SIR 9 comes in with more modern features such as a 44mm oversized headtube, allowing the use of tapered forks. The rear end gains some torsional stiffness with a 12x142mm thru-axle, and the disc brake post mounts are placed between the chain and seatstays for more braking power and precision.

The SIR 9 uses custom drawn Reynolds 853 with Double Zone Butting. This allows a lighter steel frame, and the custom bends in the downtube overcome some of the clearance issues that plague other steel 29ers. Niner is picky about the handeling of their bikes, and this allows the use of steeper headtube angles that keeps the SIR 9 fast and responsive on the trail.

Niner''s BioCentric II bottom bracket is the cleanest solution we''ve seen yet for singlespeed use, with no chain tensioners or sliding dropouts, and means your brakes are always properly adjusted.

• Available in Hot Tamale Red or Arctic White
• 44mm Headtube allows the use of tapered (1-1/8 to 1.5") steertubes or straight 1-1/8" steertube forks. Internal ZS top cup and 1.5" EC bottom cup included (ZS44/28.6 EC44/40)
• 73mm BB width with BioCentric II installed, compatible with external bearing cranksets only
• 27.2mm seatpost size
• 28.6mm front derailleur, high mount, bottom pull
• 29.6mm seat collar size (available here)
• 12x142mm rear spacing, Maxle thru-axle included
• Recommended triple crankset or SRAM 26/39 double or lower, or Shimano XT 28/40 double or lower. XTR double cranks are not recommended due to possible frame contact.