Up to 60% Off Components—Upgrade & Replace »
  • Free Shipping on orders over $50*
  • 100% Guaranteed Returns

$999.00

Item # NNR0030

4 5

Community Rating | 1 Review

Select options
  • Select options
  • Tamale Red, M ($999.00)
  • Tamale Red, XL ($999.00)
  • Arctic White, S ($999.00)
  • Arctic White, M ($999.00)
  • Arctic White, L ($999.00)
  • Arctic White, XL ($999.00)
  • Blaze Yellow, L ($999.00)
  • Blaze Yellow, M ($999.00)
  • Blaze Yellow, S ($999.00)
  • Blaze Yellow, XL ($999.00)
Compiling options for this bike.
  • 100% Guaranteed Returns

Item # NNR0030

Selected Option:

Add to cart Save add to wish list
  • 1.888.276.7130
  • Live chat

Description

Steel will always be real.

Aside from an occasional oddball, like magnesium or something from the kingdom Plantae, material choices for mountain bike frames are aluminum, steel, and carbon fiber. Each one has distinct advantages and disadvantages, and the amount of time that's been spent deviling into their nuances is unfathomable. But, based on common deductions, there are solid reasons why Niner would continue to offer an updated S.I.R. 9 among its carbon and aluminum 29ers.

The S.I.R. 9, along with the alloy AIR 9, launched Niner into mountain biking's limelight. And it's hard to believe that the S.I.R. 9 is already approaching eight revolutions of the big yellow orb since it began humiliating bouncy bikes with lesser wheels. In that time, we've seen carbon eclipse ferrous and aluminum chassis due to gram counters' love affair with fibers and epoxy. But, steel still holds its own when it comes to ride quality and value.

Most manufacturers pick either aluminum or steel for a price-point line. Niner chose to use both -- alloy for its entry level line, while reserving steel for the seasoned rider who can appreciate its distinct ride characteristics, and who doesn't need to drain a bank account on a carbon rig to chase KOM's. If you're not up to speed on the differences between steel and aluminum, the quick and dirty is that aluminum is intently stiffer and lighter, so it tends to accelerate quicker, but it can be more fatiguing due to vibration -- imaging holding onto a jackhammer all day. Steel, on the other hand, dampens trail chatter and has a natural spring-like nature that results in lively and encouraging handling on singletrack. In this case, Niner uses proprietary Reynolds 853 tubing with custom S-bend rear seatstays and chainstays. The tubing's wall thicknesses, including the down tube and top tube, are tweaked both externally and internally to produce the best possible ride quality for each frame size.

Clean TIG welds provide the strength, while short chainstays and a steep head angle offer the maneuverability that tight, twisty trails require. Niner also gave the S.I.R. 9 a radically sloping top tube for plenty of stand-over clearance in all its sizes. From the beefy tire clearance to the down tube shaped to avoid interference with fork crowns, everything about this frame shows the design time invested. And because of this extensive R & D, and willingness to use new standards and technology that benefit 29ers, Niner's developed a reputation for being ahead of the curve. Good luck trying to find another steel frame that has 142mm rear spacing, a post mount rear caliper, and the option to run just about any drivetrain configuration out there -- from single speed to multi-speed.

The S.I.R. 9 features Niner’s exclusive Bio-Centric EBB technology. An essential design element of the Bio-Centric system is that the cups lock to the bottom bracket shell’s flange. Once the EBB is in position, one bolt tightens the eccentric to the flanges, providing 360 degrees of purchase, while eliminating any chance for creak-causing dirt or debris to contaminate the interface. Also, because forces are no longer placed against the inside of the shell, it won’t round out or suffer from the over-tightening issues of traditional EBB designs.

This simple solution makes the S.I.R. 9 the true Zen-machine that SS bikes should be. The wheel can be removed without hassling with the caliper position or chain tension, and you’re guaranteed perfect dropout-to-frame alignment -- unlike individually adjustable sliding drops. All that you need to do to set up the S.I.R. 9 for gears is to add the derailleur hanger dropout and swap the EBB for one of Niner's CYA press fit adapters.

If you plan on going the geared route, Niner recommends doubles not exceeding 26/39 chainrings for SRAM, and 28/40 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.

The Niner S.I.R. 9 Mountain Bike Frame is available in the colors Arctic White and Tamale Red and in four sizes from Small to X-Large.

Tech Specs

Frame Material:
steel
Suspension:
hardtail
Recommended Fork Travel:
80 - 100 mm
Head Tube Diameter:
[upper cup] ZS44/28.6, [lower cup] EC44/40
Headset Included:
yes
Bottom Bracket Type:
Niner Bio-Centric EBB
Front Derailleur Mount:
28.6mm clamp-on, high-clamp
Derailleur Pull:
bottom
Seatpost Diameter:
27.2 mm
Cable Routing:
external
Replaceable Rear Derailleur Hanger:
yes
Compatible Components:
Shimano, SRAM
Recommended Use:
cross country racing and trail riding
Manufacturer Warranty:
2 years on frame

Geometry chart

Niner Bikes

Geometry Chart

 

S.I.R. 9
80mm Fork
 

Seat Tube

(c-t)

Effective Top Tube

(eTT)

Stack

(S)

Reach

(R)

Standover

Head Tube

(HT)

Head Tube Angle

(HTo)

Seat Tube Angle

(STo)

Bottom Bracket Drop

(BBD)

Chainstay

(CS)

Wheelbase
S 15.5in 23.2in 24.2in 15.9in 28.0in 3.9in 70.8o 73.3o 2.2in 17.3in 42.4in
M 16.5in 23.8in 24.5in 16.5in 28.8in 4.3in 71.3o 73.3o 2.2in
17.3in 42.9in
L 19.0in 24.6in 25.4in 17.0in 30.9in 4.9in 71.3o 73.3o 2.2in 17.3in 43.7in
XL 21.5in 25.3in 25.9in 17.6in 32.9in 5.7in 71.3o 73.3o 2.2in 17.3in 44.4in
100mm Fork
 

Seat Tube

(c-t)

Effective Top Tube

(eTT)

Stack

(S)

Reach

(R)

Standover

Head Tube

(HT)

Head Tube Angle

(HTo)

Seat Tube Angle

(STo)

Bottom Bracket Drop

(BBD)

Chainstay

(CS)

Wheelbase
S 15.5in 23.3in 24.4in 15.6in 28.2in 3.9in 69.8o 72.3o 1.9in 17.3in 42.7in
M 16.5in 24.0in 25.1in 16.1in 29.0in 4.3in 70.3o 72.3o 1.9in 17.3in 43.1in
L 19.0in 24.7in 25.7in 16.7in 31.1in 4.9in 70.3o 72.3o 1.9in 17.3in 43.9in
XL 21.5in 25.5in 26.4in 17.2in 33.1in 5.7in 70.3o 72.3o 1.9in 17.3in 44.7in

Niner S.I.R. 9 Geo

Reviews & Community

What do you think of the

Niner S.I.R. 9 Mountain Bike Frame

? Share a...

Write a review

No file chosen

Rather attach a photo from another website?

Rather attach a photo from your computer?

  • Product review:
  • Share a video
  • Share a photo

How familiar are you with the product?(Optional)

Only jpg, jpeg, png, gif or bmp files please.

Save

Here's what others have to say...

4 5

Modern-technology be damned, sometimes

  • Gender: Male
  • Familiarity: I've used it several times

I've loved the idea of a steel bike since the beginning. There are (literally) millions of threads and blog postings talking about why steel is still a relevant (and good) material to use for bike frames, so I won't delve into all of that. I came off a Pivot LES, and a Highball Carbon before that, so I've had my fair share of creme de la creme carbon hardtails. To feed my never-ending lust for steel, I decided to give the new SIR9 a try. The stereotypes are true - it's pretty heavy, it is really smooth (smoother in the rear than either of my previous carbon hardtails), and is relatively heavy (yep, it's like a pound or two heavier than my other frames were). But for me, especially this time of year, I don't really care all that much. I don't have to worry about damaging the frame (I suppose I need to be conscious of rusting, but FrameSaver should take care of that), and it's pretty inexpensive. And it's fun, and different. And it's easy to make it single speed or geared. I dig it - when spring rolls around and I go back to slogging up thousands of feet of vertical, my tune my change a bit, but as a cool all-around hardtail (especially for midwest riding), this thing is rad.

Modern-technology be damned, sometimes
Compiling options for this bike.
It'll be just a moment...