Material Matters: Nike Flyknit

Take a minute to think about how many different sneaker uppers you’ve seen – various construction techniques, materials, support elements – it would take a seriously long time to list them. With all of these technologies vying for superiority, the advent of an entirely new production technique and subsequent dominance of the market is an insanely big achievement. It seems like wherever you look these days there’s a knitted shoe, it was only half a decade ago that they didn’t exist. The sock-like fashion styles line the shelves of boutiques, while the high collared performance footwear dominates athletic tracks and sports arenas from the professional level down

Looking back through the annals of sneaker history there seems to have been constant to-and-fro, which would see designers sacrifice light-weight construction to build up elements of support ­– or the other way around. During the 70s runners favoured minimally reinforced nylon uppers, but the running world soon became concerned with the anatomy of the foot and the long term implications of such flimsy footwear. On top of that there was a need for shoes that could support lateral movements and different running styles, particularly as popularity for aerobic exercise and cross training grew among the wider population. During the 80s bulky shoes like the Air Trainer 1 offered unparalleled support with features like the forefoot strap and mid cut collar. At the same time Nike produced the Sock Racer, as minimal an athletic shoe as the world had seen, the textile runner was largely overlooked until later years.

Eventually athletic shoes started to take on more substantial forms with layers of leather, plastic structures, built up ankle support and adjustable fasteners. The performance advantages of well fitting, supportive sneaker had become undeniably clear, for the next few decades the quest for light-weight support would dominate the technological developments of the athletic footwear industry. Nike attempted to answer these questions with shoes like the Kukini – a rubber support cage extending across a minimal upper. In 2003 Nike even attempted to change the focus with the Mayfly, a shoe built to survive for a mere 100km, just enough to last a single marathon and its pre-event training.

In 2012 Nike presented the world with a certified game changer – the Flyknit Racer. The basic idea behind the runner was to produce a shoe that had the form fitting qualities of a sock but also static structure of a sneaker. It took Nike four years to precision engineer the woven structure so it could give support in all the right areas. After all that hard work Nike developed ways to alternate weave structure and yarn (yarn is the spun filament or fibre used to weave, as opposed to thread which is used to sew) properties to enable the upper to move in certain ways. Have you ever noticed how some fabrics stretch more in some directions than others? The incredibly clever people at Nike were able to utilise these properties, on a minute scale, to weave support into the shoe. The result is a form fitting, almost seamless shoe that weighed less and used less material than any other shoe available at the time.

True to form, Nike remained tight lipped about how they were producing the Flyknit Racer. What was clear was that a flat knitting machine was being used, creating a single piece upper with a closed selvedge all the way around and the Flywire lacing support structure woven in. They announced that they had developed variations of their own polyester yarn, each with different denier or tensile properties according to their intended use – more elasticity would be needed in areas that require stretch, for example.

Months after Nike’s Flyknit racer released adidas launched their first Primeknit shoe, the adizero Primeknit. The approach adidas took to promoting the shoe shed a bit of light on their process with the release of a video showing the production of the shoe from start to finish. The video showed the particular type of Stoll flat knitting machine they were using (pictured left), as well as a close up look at their tensioning set up and needle beds. There were obvious differences from the beginning, the Nike shoe was a much more complicated knitting pattern, while the adidas Primeknit shoe used jacquard techniques to produce its finish.

In the end, the similarities Nike saw in the adizero Primeknit were sufficient for them to take adidas to court over the patent infringements. Eventually the case was dismissed and Primeknit was back on the shelves after a short break. To this day Nike continue to battle against infringements on their Flyknit patents, most recently taking Sketchers to court over claims on multiple copyrights (the case remains unsettled). Despite all of their efforts, however, no other manufacturer has been able to construct a knitted shoe with the same precise engineering and overall quality of Nike’s Flyknit.

Aside from producing great shoes, knit technology has done big things for the footwear industry. Compared to cut and sew footwear, Flyknit construction is said to reduce the waste left over from each shoe by about 60 percent, due to the fact that there are no offcuts – between 2012 and 2016 Nike has reduced waste by over 1,500,000 kilograms. Four years after the introduction of the manufacturing, Nike completed their transition of all core yarns used in production to recycled polyester. At the time this accounted for 182 million plastic bottles being diverted from landfill.