Niner SIR 9 £1600

Silky steel big-wheeler

BikeRadar score 4.5/5

Niner is the only multi-bike brand based entirely around 29in wheels. Its devotion to the ‘big revolution’, as it calls it, is showcased beautifully in the SIR 9. This sweet handling steel hardtail is one of the most convincing and opinion-changing wagon wheel (29er) arguments we’ve ridden.

Ride & handling: Glides smoothly over the rough stuff

Everyone who rode the Niner said it felt right straight away. Whether they were experienced big wheelers, open minded novices or stubborn 29er sceptics the SIR 9 rolled over any resistance to its charms as easily as it rolled over roots and rocks.

The major benefit of 29in wheels is that obstacles are proportionately smaller to them than 26in ones. 29er wheels also have more inertia spinning them, which means less deceleration over obstacles.

What 29ers don’t do well is accelerate or change direction quickly. Longer spokes and forks plus shorter head tubes also tend to flex more, so tracking on 29ers is never as good as 26in wheeled bikes.

With this in mind Niner has concentrated on amplifying the format’s advantages. While the bike’s innate flexibility might mean a slight magnetic tendency towards deep ruts and the occasional twang off line on climbs, the dividends are what most 29er riders are looking for.

With tyres inflated to our benchmark 35psi, the Niner felt a good 10psi softer, gliding smoothly over stuff that other bikes chattered through. Long step runs, buzzing boardwalk, random rocks or frost-hard ruts; as long as you let go of the brakes and relax it melts the lot with its long, lithe frame tubes.

Despite concern over the tall 36x19 gear we found the extra speed added further smoothness to proceedings, maximising momentum and propelling us further up stuff before we had to start cranking. Get the gear turning and it gallops across open country and up long climbs like a thoroughbred.

Most impressively, handling was spot on. You still get all the stability advantages of the big wheels but we never felt tripped up or tied to straight lines when the singletrack tightened up. Even at walking pace its low weight and muscular response meant it launched out of each section with enthusiasm.

Frame: Custom butted Reynolds 853 tubes have just the right balance of spring and strength

Niner takes getting its bikes absolutely right very seriously. The Reynolds 853 steel used is the most advanced alloy around, with a beautiful blend of weld strength and spring. Niner has worked closely with Reynolds to get the butting (wall thickness change) profiles spot on for the longer tubes of the SIR 9 frame. The small and medium frames use narrower diameter tubes than the large and extra large sizes to give each the right spring/strength balance.

Both head tube and down tube get wraparound gussets to cope with long fork leverage. While most 853 frames only use the magic material on their main frames, the SIR 9 gets a full set of skinny 853 seat and chainstays too. Small bridge plates keep alignment tight without compromising mud room.

Our ride was a 2008 bike but 2009 frames get a new CNC machined asymmetric eccentric bottom bracket design, which gives perfect alignment for cranksets with external bearings. It’s the lightest eccentric chain tightening system you can get, so the SIR 9 feels anorexic for a steel frame.

Using an eccentric to take up chain slack means Niner can use normal vertical dropouts, with bolt-in blanks or a gear hanger. Cable stops may annoy purists, but the down tube routing is relatively unobtrusive. The stainless steel head badge is a nice touch, as is the luxurious metallic paintwork, in either Root Beer or Solid Gold.

Equipment: Choose your own parts, but beer bottle stem cap is a nice touch

Niner’s complete bikes come geared so this test bike is a custom build – to work out your own allow £679 for the frame.

Niner builds a specific colour-matched SIR 9 taper blade Reynolds steel rigid fork (£169), but we were impressed with the RockShox Reba Team fork on our test bike. It’s stiff enough to stop any disturbing twang and the new 2009 Black Box damping is well controlled even before you start tweaking.

It might not affect the ride, but the YAWYD (YouAreWhatYouDrink) top cap is a neat idea, allowing you to use your favourite beer bottle top as the stem top cap. 

The flat, wide but well swept Niner bars are ideal for keeping an aggressively low hand position over the tall front wheel.

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