First Impression: Niner S.I.R. 9

By Eric McKeegan

The S.I.R. 9 was one of Niner’s first models, helping to propel the 29-only company from tiny start up to a dozen models including three full-suspension platforms. Not one to forget its roots, the S.I.R. recently got a full redesign, and Niner sent us out a test bike, set up in single speed configuration.

After a late winter of sorry trail conditions, the S.I.R. arrived just in time for a trip down to Pisgah for some dry trails and big hills. Niner was nice enough to include both a RockShox SID XX suspension fork and one of its own carbon forks. Knowing Pisgah’s rep for trails full of the gnar, the suspension fork got the nod.


The rest of the build was purely cross-country, with Schwalbe Racing Ralph tires set up tubeless, a Niner flat bar, carbon seatpost, and my preferred all around singlespeed gearing of 32-20.

After some initial rude awakenings to both the realities of climbing with one gear and the limitations of XC geometry on fast, rough descents, I was stoked be back on a simple, efficient bike. Not to mention it was good training for my less-than-wise choice to race the singlespeed class at the Transylvania Epic stage race in a few weeks.

The tubes in the S.I.R. remain Reynolds 853, still one of the finest steel alloys on the market. Niner utilizes larger diameter tuning and a proprietary bent down tube and rear stays for a more precise steering and less flex while pedaling, without losing that magic ride that steel is known for.

Chain tension is handled by Niner’s BioCentric II eccentric bottom bracket. The two-bolt design distributes the clamping force over a wider area than the first generation design. At the other end of the chain are 142×12 dropouts of Niner’s own design with a replaceable derailleur hanger that can be removed for a clean look whilst singlespeeding. 

After a few hard days on this bike, I’ve been reminded how nice it is to just ride. No diddling with suspension switches, no hunting around for the just the right gear. That is the key to the single speed, your gear is always the right one, even when it feels very, very wrong.

Pick up the current issue, Dirt Rag #170, for my complete review.