Niner ROS 9 Mountain Bike Frame $899.00
Ride over it all.
Niner has built a devoted following by repeatedly showing the mountain biking world that our preconceived notions about 29-inch wheels are pretty much all wrong. The latest salvo fired in the aforementioned battle is the ROS 9 Mountain Bike Frame, a chromoly steel monster truck that's far from your average wagon-wheeled hardtail. First of all, it's strong, not light. It's built to handle years of abuse under aggressive riders. That's a good thing, because the slack head angle and tight chainstays make it clear that it’s built for going nuts on trail features, instead of chasing KOMs. Niner says it’s the hardtail for riders who don’t like hardtails, but we’re more inclined to call it old-fashioned fun, without the pretense.
The ROS looks a lot like the SIR 9 from which it's descended, but the burly steel tubeset is far better equipped to handle bigger forks and wild riding styles. As a result, the ROS frame weighs in at 6 pounds, so it's no featherweight. But as anyone who’s ever walked back to the trailhead due to a broken frame can tell you, a little extra weight is well worth the peace of mind, especially when you’re jumping that gnarly double for the first time.
A quick glance at the geometry sheet will confirm that the ROS isn’t your average hardtail. Depending on your choice of a 120mm or 140mm fork, you’ll end up with a 68- or 67-degree head angle, respectively. And in the world of 29ers, that's very slack — perfect for going fast. Out back, the chainstays hover around the 16.5-inch mark, with 5mm of fore/aft adjustability courtesy of Niner's BioCentric bottom bracket. That keeps it turning on a dime, and makes full speed manuals a piece of cake. But it doesn't sacrifice stability with its roomy cockpit and low bottom bracket.
A bike this burly isn't much good if you're stuck with flimsy components. That's where the 44mm head tube comes into play — allowing compatibility with tapered forks. The 31.6mm seat tube fits just about every dropper seatpost on the market, and the stealth routing gives you extra options. The dropouts employ a 12x142mm thru axle, enhancing stiffness and security when you're sending it. The bottom bracket shell is oversized, and includes Niner's BioCentric bottom bracket adapter, which is compatible with 73mm threaded bottom brackets. It's eccentric, so you have both geometry adjustment, and super-simple singlespeed setup options. If you prefer a geared setup, you also have the option of running Niner's CYA adapater, which accommodates all of the latest crank standards, including various oversized spindle options. 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 32t chainring, and when in the forward position, it will accept a 38t ring. It’ll clear just about every 2.3in tire on the market, and there's clearance for double and triple chainring cranksets. In other words, it'll handle any setup that your riding warrants.
The Niner ROS 9 Mountain Bike Frame is available in four sizes from Small to X-Large and in the colors Forge Grey and Niner Blue.
What community has to say
Excellent write-up of this bike/frame on Vital: