How aerospace inspired Nike cushioning
Nike's Lunarlon foam drew inspiration from the American moon landings and finally came to life as an ultra-lightweight foam in some of Nike's top performance footwear.
By Striperpedia staff
When astronauts first bounded across the surface of the moon in 1969, they hardly could have imagined they were inspiring a cushioning technology for a new generation of sneakers.
It was an indirect route from the moon’s surface to the Earth’s. Nike reflected its own admiration for that massive aerospace accomplishment by introducing the Moon Shoe in 1972. Fast-forward to 2004, and it was the Waffle outsole on that shoe that inspired Kevin Hoffer to spearhead the development of Lunarlon cushioning.
“A co-worker and I were looking through a flipbook on the genealogy of speed and what begat what, as far as lineage,” says Hoffer, Nike’s Innovation Lead, who recently sat down for an exclusive discussion with Striperpedia. “As we were checking it out (the Moon Shoe), we saw the quote from Geoff Hollister, who we both know.”
Hollister was one of Nike’s earliest employees in 1971 when he strapped on the company’s first Waffle outsole and said, “It was like running on pillows.”
Hoffer continued: “At the time there was a debate around what’s the future of lightweight. There was the Mayfly at the time, an ultra-lightweight marathon shoe. It was very cool … but honestly not a lot of people could go hammer out a marathon in it. So where do we go from there? We could take another ounce out of it. But we needed a paradigm shift.”
The Mayfly came on the scene in 2004. Virtually a disposable shoe, it cost just $45, weighed just 4.8 ounces, and a runner could expect about 62 miles out of it. This mind-set was something Hoffer wanted to evolve from a specific shoe to an altogether new technology that could cross shoe genres.
“Hollister was talking about an experience,” Hoffer said, “an ultra-lightweight experience. How do we do that today? That’s the whole impetus behind Lunar.”
Hoffer, who has contributed to 15 recorded patents, put his innovation cap back on and met with Nike’s Advanced Materials Research technicians. They started hashing out specs with chemical engineers.
“If you go really lightweight, you end up with Styrofoam,” Hoffer said. “We found one thing back in the archives – a foam rubber/blown rubber – that’s used in aerospace. You pump a ton of blowing agent into it; you take this chemical that blows it into a foam. You felt it; it was super-lightweight, you’d squeeze it in your hand and it springs right back.”
Hoffer and his team quickly realized that initial iteration was untenable.
“You can’t use it,” he said. “Rubber was way too expensive, it wanted to shrink, it was super-sticky ... there were a lot of complications. But you could feel it and would say, ‘Wow, this is really special.’”
After a few ruined molds, Hoffer and his team had some samples.
“As soon as we got it on the feet of runners,” he says, “it was like they were addicted to it. That’s what kept us going.”
Fine-tuning the initial Lunarlon included the humorous twist of having to store wedges of foam, which resembled ice cream bars, in freezers all over Nike’s Innovation Kitchen.
“We knew it had to have a Phylon shell,” Hoffer recalls. “We had to put it into a freezer just to keep it stable enough so we could get everything to glue together.”
The freezer solution was temporary as a more market-ready picture of Lunarlon gradually came into focus. Lunarlon weighs about 30% less than the company’s standard ethylene vinyl acetate (EVA) foam, according to Nike.
“It’s definitely softer, more energy-efficient, and springier,” Hoffer said. “Which is why we have to encapsulate it in this shell. We’ve tried to make a whole midsole out of it, but it’s way too unstable. … The rubber is what gives it the integrity and the springiness.”
Nearing the finish line
Live testing with real athletes really helped Lunarlon hit the home stretch toward market-readiness. Runners from Oregon and Stanford universities lent their feedback, as did local running clubs.
“It was the end of ’05/early ’06 by the time we had stuff coming out of the freezers,” Hoffer says. “Once we had initial prototypes we knew we had some paydirt. But early on, you can’t afford the materials, it’s super-sticky … it’s more a question of how do you scale this up for production in three countries and five factories? It’s one thing to jam stuff into a freezer in a machine shop; it’s another to scale it up for mass-production.”
After more than three years of development, Lunarlon finally went to market in the fall of 2008 as part of the Nike LunaRacer, the Nike Lunar Trainer and the Nike Hyperdunk (the Beijing pack). Today Lunarlon cushioning can be found in dozens of styles for men, women and kids. It’s most commonly used in running and basketball, and at price points from premium to entry level.
Differentiating the usage between running and basketball proved to be an epiphany for Team Hoffer. Lunarlon can be found more commonly in running shoes because it takes more material in order to stabilize it against the extreme cuts – often by larger athletes – in basketball.
“We use three different grades, a 1, a 2 or a 3,” Hoffer says. “1 is the softest, 3 is the firmest. There’s more rubber as you get up into 3. Most running uses 2. Basketball and training use a 3. It’s not a huge jump, but it’s the same basic chemistry; one has a pinch more rubber than the other.”
Hoffer found the 1-grade too unstable to be commercially viable at the time. But running was a good fit for 2-grade, and basketball for the 3-grade.
What’s next for Lunarlon?
The popularity of Lunarlon has spread across silos, and Nike figures to continue to implement it where it makes sense for wearers.
“It’s a platform technology, like Nike Air,” Hoffer said. “It’s not some flash-in-the-pan thing; it’s definitely something we’re investing in.
“Like most technologies, when they hit, people are curious about them and how they might be appropriate for what they need. That’s when we start experimenting; that’s when we came up with the three grades of Lunarlon foam. We started with 1; it was a little too soft, so we bumped it up to 2, which was good for running. 3 was for basketball, and those athletes had a higher response to it.”