The Niner S.I.R. 9 SPX Rigid (Carbon Fork) 2011 Mountain Bike is the most versatile bike in the Niner stable, fusing the ''steel is real'' feel of Reynolds tubing with the ability to run the frame as either a geared bike or single speed. The S.I.R. 9 uses the same custom drawn Reynolds 853 tubing as the M.C.R. 9 and combines it with Niner's ultra-light eccentric bottom bracket. Custom ''breezer'' style forged dropouts have a replaceable alloy derailleur hanger and come with an insert piece for running the bike as a single speed to eliminate the unnecessary derailleur hanger for a clean look.
Niner's own EBB, at 100 grams, is the lightest eccentric bottom bracket on the market. In addition to being light, it's extremely functional. The EBB has more swing than any other EBB, over a full link, so you will never have to hunt down a half link to get correct chain tension and vertical dropouts mean you'll never have to futz with the disc brake to remove the wheel. The S.I.R. 9 is truly a do-everything frame. Run it single speed at your local race, then convert it to a full gear set to do the Trans-Alp. Want a 1 x 9? No problem. Or, if you're just not sure, the S.I.R. 9 will give you the option of trying it all.