For several years, footwear manufacturers of all kinds have been expanding minimalist shoe options. Minimalism is typically focused on the sole of the shoe, where cushioning and materials are cut down to provide a more natural step. Essentially, these shoes give you just enough material to protect you from cuts and injury while staying out of the way of your bio-mechanics.
With the Flyknits, Nike extends minimalistic design to the upper part of the shoe. The single-layer uppers give you material only in places that you need it, cutting weight when compared to the thicker uppers of other shoes. The entire upper and tongue weigh just 1.2 oz (34 grams), while an entire size 9 shoe weighs 5.6 oz (160 g). Nike says the Flyknits are 19 percent lighter than its Zoom Streak 3, a shoe worn by the first, second and third place finishers in the 2011 World Championships men's marathon.
Flyknits are not quite as minimal as Swiss Protection Socks, but the motivation was the same. Nike developed the Flyknit design based around input from runners that yearned for a shoe with the lightweight fit of a sock. Nike says that it spent four years developing the proper application of lightweight, pliable knit material with the solid, stable properties necessary for a shoe. Unlike regular sock material, which wouldn't provide enough support or durability to serve as a shoe, Nike's micro-engineered knit uppers reportedly give athletes the light, form-fitting feel of a sock with enough rigidity to support the foot and hold up to repeated use.
Nike analyzed the needs of runners and engineered specific areas of the upper to give runners flex, support and breathability where they need it. Given its hole-filled, single-layer construction, we'd expect that it will be cooler on long summer runs. Your socks may get a bit dirtier, though.
Flyknit technology will launch in the Flyknit Racer, which marathon runners from Kenya, Great Britain, Russia and the U.S. will wear this spring. That shoe and a slightly heavier, everyday training shoe called the Flyknit Trainer+ will hit the market in July. Nike will also offer Flyknit construction in the HTM Flyknit series, which experiments with different colors and patterns.
The video below is essentially the Flyknit concept animated.