Out Of The Box: Niner AIR 9

Out Of The Box: Niner AIR 9- by Grannygear

In the beginning there were some guys in Colorado and likely other places that had this silly idea that bigger wheels on mountain bikes made sense. Yeah, right. Who would buy those? Then some co-visionaires began putting some money and muscle into that dream, guys like Gary Fisher for instance, and things began to get rolling. Along comes Niner bikes. Steve and Chris were bold enough to actually begin a brand new bike company that was 100% devoted to 29″ wheeled mountain bikes. What chutzpa? Da’ noive of those guys!

Fast forward to today and Niner Bikes is still here, still growing, and still all 29″ers. So on test is the newest version of the Air 9 alloy hard tail in the XL/22″ size. Yeah, I know the buzz is all about carbon these days, but carbon frames, at least proven ones, are still pretty high priced and are likely to stay that way. If steel is the common man’s trail/XC hard tail of choice, then aluminum is the common man’s racing material of choice. Aluminum is light, cheap(ish), easily formed into complex tube shapes, and stiff enough to give you great power transfer and direct steering, something any XC racer (or hard charging XC rider) likes to have. The welding of things like this Aluminium box section could be fairly straightforward which is why its use is considered preferable by some welders.

For this new year, Niner moved away from Scandium, an aluminum alloy as well, and back to a 6000 seres based aluminum tube set. The impetus to this seems to be more than just a new marketing scheme as 6000 series aluminum, as I understand it, is much more willing to be hydroformed into new shapes than Scandium which is pretty thin and brittle…so I have been told. And the new Niner AIR 9 is all about hydroforming. Now I am no engineer, but as I have the power of the internet at my command, here is a Wikipedia section on the technique.

“Hydroforming is a cost-effective way of shaping ductile metals such as aluminum, brass, low alloy steels, stainless steel into lightweight, structurally stiff and strong pieces. One of the largest applications of hydroforming is the automotive industry, which makes use of the complex shapes possible by hydroforming to produce stronger, lighter, and more rigid unibody structures for vehicles. This technique is particularly popular with the high-end sports car industry and is also frequently employed in the shaping of aluminium tubes for bicycle frames. Hydroforming is a specialized type of die forming that uses a high pressure hydraulic fluid to press room temperature working material into a die. To hydroform aluminum into a vehicle’s frame rail, a hollow tube of aluminum is placed inside a negative mold that has the shape of the desired result. High pressure hydraulic pumps then inject fluid at very high pressure inside the aluminum which causes it to expand until it matches the mold. The hydroformed aluminum is then removed from the mold. Hydroforming allows complex shapes with concavities to be formed, which would be difficult or impossible with standard solid die stamping. Hydroformed parts can often be made with a higher stiffness-to-weight ratio and at a lower per unit cost than traditional stamped or stamped and welded parts. Virtually all metals capable of cold forming can be hydroformed, including aluminum, brass, carbon and stainless steel, copper, and high strength alloys.“

Molding of this type is also used in manufacturing industries to make utensils, automobile parts, and so on. In fact, almost nothing can be manufactured without heat treating, a process that involves heating and cooling metal under strict control to improve its properties, performance, and durability. For example, automotive castings are done by heat treating aluminum to improve hardness and strength; brass and bronze items are heat-treated to increase strength and prevent cracking; titanium alloy structures are heat-treated to improve strength at high temperatures.

However, at times, if the connection on a typical bearing is secured by a press-fit, the metal-to-metal contact area between the components is only 30% of the total joint surface area. As a result, small movements at the joint interface grind down the parts and cause abrasion to produce small particles. In such cases, using adhesives designed specifically for such bearings (loctite 638, for example) may solve the problem.

So you take a boring old round tube of aluminum and pop it out like a beer can into all these nifty shapes and weld it into a bike frame. Just marketing bilge, right? Hardly. A shaped tube like this is what is making aluminum viable for 2013 29er riders. Some of the new manufacturing techniques for aluminum that I have been talking about to one engineer of a large bike company tends to make me think that in the next few years aluminum will see a high tech resurgence and will hardly fade away to the realm of cheap MallyWart bikes.

All that said, here is what Niner says about the revised AIR 9 on their website: