Free Form Running Shoe Design
Tobie Hatfield of Nike's Innovation Kitchen talks Free, barefoot running, and experimenting
The Nike Free line isn't just about barefoot running, but freeing the foot to return to its natural movement.
By Striperpedia staff
Losing one's way is bad enough in the running world; be it on a trail, or down an unfamiliar street. But losing the way in the manufacture of world-renown running shoes can prove fatal in the business world.
Such was the challenge that faced Tobie Hatfield and his designers in the Innovation Kitchen at Nike's World Headquarters in Beaverton, Ore. And it's that dramatic yank back to reality that got Hatfield and company thinking about the newest wave in shoe design, that of minimalism, or natural foot movement.
Hatfield shed sweat and blood — literally, to hear him tell of the X-Acto knives that slipped and slashed open his leg in the design studio — as the point man in developing the Nike Free continuum. This scale measures (from 0.0 to 10.0) how close to barefoot a shoe feels. Zero represents a pure barefoot feel, while 10 is a more traditional running shoe.
Hatfield, whose older brother Tinker Hatfield has designed most of the Air Jordans, joined Nike in 1990. Hatfield the younger recently spoke with Striperpedia about the Nike Free line of running shoes, about the scale that guides runners toward natural foot movement, and about the dangers of designing with sharp objects.
Striperpedia: How did the Nike Free continuum come about?
Tobie Hatfield: In the early 2000's, we were observing coaches and athletes running and training barefoot on grass. Upon this observation and claims that this training method helped reduce injuries, we began to study the potential performance benefits of training barefoot.
We were looking at close-to-barefoot first, and our initial prototypes mimicked barefoot motion. The first prototypes, which no one's seen unless they were here, were very minimal, but we thought, "Most people have never trained barefoot before, and it wouldn't be best for them to go all the way to zero. It's like a strength training program; you wouldn't go into the gym for the first time in years and bench press your max. You need to build strength over time. We have a responsibility to do this the right way and let the runner progress naturally into barefoot training.",
On the 0-10 Free continuum, Zero is barefoot and 10 is a more traditional running shoe, so we sought to start in the middle of the scale at a 5.
The numbering was more internal to start with, but consumers gravitated toward the scale. There will be some people who will start at a 5 and stay at a 5. Then there'll be others who will progress really quickly to a 3.0 and, if we go further, to close to barefoot.
Again, athletes train in a progressive manner. They don't go in the first day and lift their heaviest weight. If they're training for a marathon, they don't do 26.2 miles their first day; they progress to that.
Abebe Bikila brought barefoot running into international consciousness when he won gold at the Rome Olympiad in 1960. Why is the movement toward barefoot-minimalism just coming about now?
Hatfield: We listened to our athletes and our coaches. They said we were starting to lose our way with the shoes — not just Nike but the industry. We'd forgotten about the foot. We need to celebrate the foot. Leonardo da Vinci said the foot was a masterpiece of engineering and a work of art. He didn't say that about the brain or the heart; he said that about the foot. Yet we almost forget about it.
When we observed coaches and athletes, including former USC Coach Vin Lananna, running and training barefoot, they were running on the pristine grass of Stanford's golf course, which most people don?t have access to. That's one of the great things about shoes ? they protect you from the elements and from stepping on debris like glass. So we said, "Let's retain that, but only that, and let the foot do everything else.",
That's how it started in 2000-2001. Barefoot running is not a new idea. The new idea is replicating barefoot training in a shod condition.
What has been the greatest challenge to developing this continuum?
Hatfield: We did a 5.0 to start with and immediately thought, "Let's go down this continuum and do a 4.0.", We knew how to measure that; we could put a number to any shoe you gave us by measuring the different angles of the joints, the metatarsals, pressure points. The problem was, when you went from 5 to 4, could the user perceive the difference? We measured; it was a 4, but perception-wise, would people think, "I don't know if this is much freer than a 5",? We needed to stay on the odd number system and go from a 5 to a 3. Sure enough, after that we went to a 7.
One other challenge has been communication of the numbering system/continuum itself; just getting it started. Once you start talking to people about it, then not only do they get it, but they expect it. That's what we saw when we took the numbers off.
Stripping away materials must be a new approach for shoe designers. What has been an "aha" moment of discovery for Nike's designers in developing the Free line?
Hatfield: Several! One that comes to mind immediately — once we did a more natural-motion type last — had more contours in the top of the footbed. So the foot fits in there more like a puzzle piece because you have the heel, arch and a transverse arch. Those aren't flat. So we asked, "What do we have to do to counter that movement?",
Well, then you need a heel counter, then extra overlays. That's where the overbuilding process starts to happen. So if you have a surface that mirrors the bottom of the foot better, then your foot won?t move around on the footbed so much. Maybe you won?t need so much on the upper.
I said, "Maybe we won't need a counter.", Then, to test that theory, we put the counter back in. They hated it. We don't need them, and we put them there in the first place. If you don't have that first reason, you don't need that second reason.
We knew we'd have to release tension in the midsole and outsole to allow it to flex better and the foot to flex better and not the shoe. If you don't have as much movement on the footbed you don't need as much on the upper. With a deep heel bed, the foot doesn't want to move around as much as it wanted to when it was a flat surface. Round on flat: not so good. Round seated into the footbed: better.
Nike currently produces a Free 3.0 and 7.0; what will it take to develop a 2.0 or 1.0? How close can you see getting to a 0.0?
Hatfield: Initial prototypes were very close to barefoot. We know how to do that. So we're real close. We need more research on the benefits of being down at a 1.0. We don't want to design and build and sell anything to the consumers unless we can say there's a good reason.
For example, we know most of our testing has been done on grass. But we know most people just aren't going to do that. They're going to be running on pavement. Having a 1.0, knowing it's going to be out there — if we can honestly do our research and can say, "You gain, for example, 20% in strength, 10% flexibility, balance 20%,", then great! We'll do it. But in order to get it to a successful level, we need to say, ?Here's our research to prove it.?
You've described Nike's Free line as NOT part of the barefoot/minimalist movement but rather a progression toward natural movement. Can you elaborate on the difference?
Hatfield: I really feel that anybody can make a real minimal shoe by lowering the profile and using less material or thinner materials under the foot. People can do that in their garage or professionally.
What we've found, in order to do this correctly, is that we need to replicate natural, bare motion. That's why we have the siping pattern on the outsole — to simulate barefoot movement and give runners a fuller range of motion. I've gone through lot of blood — literally, with X-Acto knives slipping and going into my thigh. We knew we wanted to be accurate because the foot was asking for that.
We began by looking at the foot itself. We can't design anything until we understand the foot. You can deconstruct anything and say, "Now just go wear it.", Is that truly going to work for the foot? A result of that appears to be that shoes are becoming more minimal/deconstructed.
The barefoot enthusiasts might say, "That isn't barefoot!", Well, they're right ? it's halfway. This is a safer, better way to adapt your foot to barefoot training.
You've suggested that the Frees be used in conjunction with other training shoes. But if the Frees are intended to promote a midfoot/forefoot footstrike, won't moving back to traditional trainers force runners to change their gait back to a heelstrike?
Hatfield: It depends how far down the continuum you go. We still have an 8mm offset, a certain amount of heelstrike. Even in 3.0, it's a little flatter. The main objective of the 3.0 is, when you go back to your Skylon or Pegasus, that it makes your experience that much better. Don?t forget, the Pegasus or Skylon is getting more flexible as well.
We view Nike Free as a training tool. Are some going to use it as an everyday training shoe? Yes, and that's great for some. Others will use the shoe as a training tool, and that's how we see it. It's very personal. For me, maybe I'll use Free once or twice a week, then I'll go back into my other shoe.
That's what I love about Nike Free. We didn't scare people away with the 5.0. There was a certain measure of heel lift. Some people may stop there, and some people may progress. That's the key — we're providing athletes with a valuable training tool.