In Berlin in September 2017, runner Eliud Kipchoge attempted to break his own world record for fastest marathon ever. The conditions were far from ideal, with heavy rain and 99 percent humidity, and while Kipchoge came in first place, he didn’t break the record. Though he was wearing specialized running shoes, Nike Zoom Vaporfly Elites, they were no match for the wet conditions, and the water his shoes soaked up added extra weight, slowing him down.
Otherwise, Kipchoge said, the shoes were perfect, so Nike decided to keep the tooling of the Vaporfly Elite and work on improving the upper so it wouldn’t absorb water. The company had been experimenting with a 3D printed upper, so they brought that out and applied it to the Vaporfly Elite, developing a new shoe called the Nike Flyprint. Although Nike has created partially 3D printed shoes for professional athletes and collaborated with 3D printing companies for footwear solutions before, this is their first shoe with a 3D printed upper – in fact, it’s the first piece of performance footwear with a 3D printed textile upper anywhere.
Nike used TPU filament to 3D print the Flyprint, using data they gathered from Kipchoge to create the ideal material composition. After creating thousands of possible prototypes, they provided the runner with an initial test version of the shoe, letting him try it out and provide feedback. His comments allowed the Nike team to make changes to the design in a matter of hours and ship the next version to Kipchoge in Kenya in a little over a week. After another round of feedback and adjustments, Kipchoge approved the next version, saying that he was ready to wear them in his next marathon, in London.
Using 3D printing, Nike was able to prototype its shoes 16 times faster than any other manufacturing method, with excellent precision. 3D printed textiles have an additional advantage over their traditional counterparts, too.
“One interesting benefit of 3D textiles over traditional 2D fabrics is the increased dynamism made possible by adding an interconnection beyond a warp and weft; an advantage of Flyprint textiles comes in the fused nature of the material,” states Nike. “For example, whereas in a knit or woven textile there is frictional resistance between the interlaced (warp and weft) yarns, in a printed textile, due to its fused intersections, there is greater potential for precision-tuned containment. It is also lighter and more breathable than Nike’s previously employed textiles.”
In addition, single lines of the material can be adjusted while preserving the construction as a whole, and the textile works seamlessly with other materials, particularly Nike’s Flyknit yarn, which can be engineered to thermally bond with the Flyprint textile, eliminating the need for glue or stitches.
The final product was named the Nike Zoom Vaporfly Elite Flyprint shoe, made especially for Kipchoge but designed to help all runners run their fastest. Kipchoge kept detailed logs while training with the shoes, and told Nike that he loved the feeling of air flowing over his foot and would run in them rain or shine. The Flyprint shoes are 11 grams lighter than the pair Kipchoge wore in Berlin, and don’t absorb water that would weigh them down.
As additive manufacturing takes a larger role in the future of footwear, several other major manufacturers have created partially 3D printed running shoes, but Nike’s 3D printed uppers are a big step closer to creating a running shoe that is 100% 3D printed. That would mean unprecedented customization for athletes, as well as additional benefits like lighter weight and much faster prototyping cycles.
Kipchoge will run his next marathon in London this upcoming weekend, on April 22nd. Over that weekend, a limited run of the 3D printed shoes will be sold in London through the Nike app.
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