Material Matters: Outwit, Outsole, Outlast
There’s simple beauty in the underappreciated outsole. Granted, it’s generally not the sexiest element of any shoe – particularly once it starts to acquire a nice coating of street grime. But, with the recent focus on urban adventure style, chunky treads have come into focus, so we thought it was about time we shed some light on where the sun don’t shine. Shoes like the adidas Seeulater or Nike KMTR wear their aggressive tread with an air of pride, while the lines running up from the sole of a Yeezy BOOST 350 are a defining feature. If you’re still not convinced of the joys of the humble tread pattern, then this one’s for you.
Mountains will always be treacherous, but before the days of synthetic fabrics, purpose-made ropes and strength-tested gear, climbing them was a pursuit reserved for madmen. After seeing six of his friends pass away on a 1935 expedition in the Italian Alps, Vitale Bramani was determined to create a safer alternative to the hobnailed leather soles to which he attributed the accident that took their lives. What Bramani came up with is one of the most iconic tread patterns ever: the first rubber lugged sole, known as Carrarmato (or tank tread, often referred to as Commando nowadays), characterised by radiating outer bars and inner star studs. Two years later, with a little help from Pirelli Tyres, the design was patented and Vibram was born.
On June 3, 1950, Maurice Herzog and Louis Lachenal became the first people in recorded history to reach the heights of an 8,000 metre peak when they summited Annapurna in the Himalayas. Though both climbers lost toes to frostbite, there’s no doubt that their cutting edge Vibram-soled boots played a big part in their successful push to the top – as noted repeatedly by Herzog in his account of the expedition. Four years later, Vibram soles were worn by an Italian expedition during the first ascent of K2. To this day, Annapurna and K2 are credited as being the deadliest mountains in the world.
With such an impressive resume, Vibram soles became the go-to for mountaineers and the virtues of well laid out rubber tread were extolled around the world. The reason the design worked so well – compared to the older styles – was due to a few factors, but it was mainly thanks to the increased friction that the tread allowed for on a variety of surfaces, which meant the shoes were a lot less likely to slip out from under the climbers when weighted.
Though the outdoors industry was awash with moulded rubber sole designs by the early 60s, the world of athletic footwear would take a little longer to catch up. Up until 1971, most sneaker soles used rows of raised ridges or simple dimples to increase surface area and friction – but then Bill Bowerman tore apart a waffle iron and poured hot rubber into the reverse side of the hot plate, and a year later the world was formally introduced to the Nike Waffle Racer.
Of course, until this point running shoes hadn’t required such aggressive tread patterns. Sports such as basketball and tennis were played on fairly consistent surfaces and runners were content with spikes. The impetus for Bowerman’s design was the changing nature of athletic tracks; a lot of arenas were transitioning from grass and dirt tracks, where spikes reigned supreme, into artificial surfaces that weren’t being overly regulated. The waffle sole was born from a need to have a more versatile shoe, an all-rounder. The advent of the cups sole in the mid 70s allowed shoe designers to approach tread from a fresh perspective, due to the new moulding technology that allowed for more complex shapes and patterns to be produced. Prime examples are the iconic radial patterns on the Nike Dunk and Air Force 1, which were perfect for the lateral movement of basketball. Or the adidas Marathon Trainer, a heavy-duty off-road runner with a similar design to the classic Carrarmato that used Trefoils in place of the original bars and stars.
As the industry set its sights on the next decade, a bundle of advancements in both production and polymer technology enabled all kinds of new tread. For example, New Balance laced their 990 with Vibram’s Superflex outsole, made from blown rubber to achieve the same tread with more flexibility. Then, in the late 80s, the planets aligned for the friction faction – and sole design was about to reach new heights.
The sneaker industry took a shine to outdoor sports such as hiking and trail running (thanks to a boom in the popularity of such activities) as evidenced by Nike’s quickly growing ACG line, which was born after climbers on K2 took to kicking about base camp in waffle soles. There was money to be made in the hills, moulding technology was pushing ahead, and then the final piece of the puzzle fell into place: computer-aided modelling. All of a sudden, designers could draw up sole patterns in a computer and get accurate information on their friction coefficient. Did you ever notice how crazy sole patterns got in the early 90s? Just look at the CB 34 ‘Sir Charles’ spell-out (probably not created for solely practical reasons). Although, novelty can sometimes co-exist with functionality, like on the Air Jordan 23 that used the Jumpman’s fingerprint pattern to form its tread, which actually made for a perfect on-court pattern.
Novelty aside, the 90s was when sole tread became a true science. The revolutionary ACG Air Revaderchi was made to function like a mountain bike tyre, channelling mud out the sides to keep traction at a maximum. Once again the tricky terrain of the great outdoors was pushing sole design forward and off-roaders began to rock tread patterns that looked more and more tyre-like. Even today, the outdoors still require the most extreme outsole patterning – none more so than the Reebok ATV 19+, an off-road trainer that takes the notion of a lugged sole to the absolute extreme. But the wilderness isn’t the only place seeing progression in tread tech. The wild, concentric lines that flow around the bottom of the React Hyperdunk 2017 were designed using pressure maps and motion capture software, some pretty advanced techniques compared to the early days of lugs and herringbone patterns.
Nowadays, designing a new outsole is often the most expensive part of producing a new shoe. For example, a Nike shoe with custom Air bags peeking out could be upwards of $25,000 in tooling costs per size, before a single sole is produced.
Next time you slip into a new pair of shoes, flip them over for a second and give the tread the credit it’s due. Traction, control and comfort all stem from those humble bumps and lines beneath your sole. You never know, those little lumps might just save your life some day.
Material Matters is our weekly tech section where we peek behind the mesh curtain and examine the building blocks of the industry. Recently, we’ve looked at Reservations on Elevation, Fables of The Forgotten and A Brief History of Yeezy.