Boing!

By 1990, John Tawney, director of Nike id, had arrived at the company from Ford Motor Co. "There were all these failed samples and boxes of parts and things lying around," Tawney, 37, recalls. "But I saw what they were trying to do, and I got the impression that there was something special to be had there."

Tawney and Kilgore's group had run out of money to pay the company that had suggested the cantilever shoe, but the company gave them one last bit of advice. "They said that our best chance was to put cylindrical tubes through the shoe," Kilgore says. He dutifully went around to all of the big thermoplastic manufacturers in search of the right material, but none of the compounds were supple enough to bounce back to their original shape after a runner's foot had stomped them down. Eventually, it occurred to the team to turn the columns vertically, and soon Kilgore stumbled onto another automotive company, one that made jounce bumpers, which are used in automobiles to absorb shocks from rough roads.

"They had springs made out of this high-density foam material that could withstand 100,000 miles of driving," Tawney says. "If you jump on a metal spring, at some point it will deform and hit a solid stop. You hit the bottom and it goes 'Kaboom!' With the foam springs, you get both deformation of the geometry and compression of the material. It is the compression of the foam material that allows us to avoid the abrupt bottoming-out point experienced with springs made from solid materials." Eventually, the team produced a four-column prototype that resembled today's Shox. Team members began limited testing on real runners, who were, for the most part, delighted by the way the shoes felt.

Meanwhile, back in the part of Nike where engineers and designers were actually producing revenue, shoes with Air technology were flying off the shelves. Michael Jordan was about to win the first of his six NBA championships. Bo Jackson knew football, he knew baseball, and he definitely knew how to sell his Air cross-trainers to the youth of America. So the company wisely decided to focus almost all of its energy on refining the Air technology and getting it into new shoes. To Kilgore, Tawney, and those who were working with them, this made perfect sense. The springs went back on the shelf, and people went to work on other projects.

Get Set: The Inspiration

In the first half of the 1990s, most everyone at Nike was busy making and selling Air shoes. But by then, there were also a lot of people who had gotten their hands on the spring-loaded-shoe samples. Many of them couldn't resist taking the shoes out of their bottom drawer every so often and walking around in them. By the end of 1997, brand-innovation group director David Bond, 37, got his hands on a pair, and he wondered aloud why the shoes had been allowed to languish for so long. Soon, a new group of engineers and designers got permission to start playing around with the prototypes, with Kilgore and Tawney serving as consultants.

Like Kilgore and Tawney before them, this new group turned to two unheralded but crucial departments at Nike to help them test prototypes. At the sports-research lab, biomechanics researcher Gordon Valiant, 47, was busy wiring testers' muscles to various machines to see how they responded to the shoes. The lab is equipped with high-speed video cameras that help researchers apply physics to the study of human movement. Over the years, Michael Jordan, Marion Jones, and many other athletes -- from the famous to the average -- have passed through the lab to serve as subjects for study.

On the same floor, Jeff Winston, the director of material and mechanical testing, was exerting every effort to make the prototypes fall apart. His lab is filled with more than $1 million worth of test equipment -- machinery that examines how shoes stand up to sweat, rain, and the different surfaces they may encounter underfoot. Working with the shoes that would become Shox, he removed the columns from under the heel and put them on machines that could rapidly push them up and down. "We can put 1,000 miles on these things in 30 hours," Winston, 45, says. "Testing out in the field takes much longer, plus all is lost if testers drop out because they've hurt themselves or gotten bored and stopped running."

As Winston was busy figuring out which columns would chunk up and fall apart, design teams for the new shoe began to form around the three biggest sport-shoe categories: basketball, cross-training, and running. Designers and engineers racked their brains to consider the individual needs of athletes in each category and how the placement of the columns would affect cushioning and stability. They also began to think about what the shoes might actually look like once the technical details that would assure optimal performance had been worked out.