The award for best ride quality has always gone to steel. That's where the Niner S. I. R. 9 frame shines. The S. I. R. 9 isn't just steel, it's Reynolds 853 one of the best, most respected steel alloys for bicycle frame building. Because of this, the S. I. R. 9 has that legendary ride quality that everyone else is chasing. Sure, it may be a little heavier than your dentist's carbon fiber frame, which costs more than your car, but it rides better. And, while we agree that the S. I. R. 9 is a little bit old school, it isn't behind the times. You get 142mm rear spacing, a post mount rear caliper, and the option to run just about any drivetrain configuration out there, from singlespeed to 33 speed. The secret behind all this drivetrain diversity is the eccentric bottom bracket. The EBB makes setup simple, unlike individual adjustable dropouts. If you plan on going the geared route, Niner recommends doubles not exceeding 2639 chainrings for SRAM, and 2840 for Shimano. However, a standard triple will pose no problems. The rear triangle will accommodate a 2. 4in tire, and you can run a 160mm rear rotor. You'll need a bottom pull, high mount front derailleur with a 28. 6mm clamp. The S. I. R. 9 uses a 27. 2mm seatpost, a 73mm BB only external style bottom brackets work with the EBB, and a 44mm tapered headset. The maximum chainring size varies depending on the position of the BioCentric EBB insert. At the most rearward position, the Niner recommends running no larger than a 30t chainring, and when in the forward position, it will accept a 36t ring. It comes with a Maxle rear axle.