For the past three years, the world of running has been obsessed with one technology: carbon-fiber plates. The springy plates that help to push runners forward are now used by almost all running shoe manufacturers in their top-end shoes. But as sports companies have raced to embed the carbon plates in their running shoes, the foot-hugging fabric material that sits on the top of trainers has been neglected.
That is, until now. Adidas has revealed that for the last four years its computer and sports scientists have been secretly working on a brand new way to create a shoe’s upper. Called “Futurecraft.Strung,” the technology sees a robot quickly place more than a thousand individual threads at mind-bending angles across the material part of the shoe.
To create this stringy canvas, the company built custom robotics and software, and conducted high-resolution scans of how runners’ feet move as they travel. For its prototype shoe (above) to demonstrate the tech, Adidas combined the new material process with a 3D-printed sole to create one of the brand’s most advanced shoes to date.
While the Strung fabric will initially be used in running shoes—the first versions won’t be available until late 2021 or even 2022—the company is already looking at how the new process can be used across other products it makes.
“There have basically been two ways to make a textile: there’s weaving, and there’s knitting,” says Fionn Corcoran-Tadd, an innovation designer at Adidas’ Futurecraft lab, where Strung was created. The lab most recently made fully recyclable Loop trainers and 3D-printed trainers. Andrea Nieto, also an innovation designer, adds: “We can work and place yarns in any direction, allowing us to create a dynamic textile.”
If the shoe’s upper material looks a little chaotic, that’s because it is. Traditional fabric manufacturing usually only allows for threads to be placed horizontally or vertically. For instance, Nike’s Flyknit technology is fashioned by knitting small squares. The patterns in the material are often repeated.
Strung turns this on its head. The upper has multiple layers of individual threads placed across the shoe. Yarns are placed at all different angles—although not at random. The gaps between the threads vary, and the threads can all be tuned to have different properties, the team behind the technology says.
“There’s a thread that’s only used in the heel region,” Corcoran-Tadd says, “because it’s by far the stiffest thread that we use in the upper. That was the area where we needed to create the most support without much stretch.” Whereas across the middle of the foot, towards the toes, there are fewer threads, as there doesn’t need to be as much support for that part of the foot. Plus, fewer threads means greater breathability. Look closely and there are visible gaps in the upper.