Inside Access: The Science of Traction

Like the cover of a book, you can’t judge a shoe by its upper.  The outsole traction and grip of a basketball shoe can make or break its on-court performance; it can even mark the difference between a good shoe and a great one.

Nike Basketball has over 42 years of experience in traction technology.  Based on athlete input, Nike has developed a four-part formula to evaluate the effectiveness of traction: surface type (indoor, outdoor or both), design pattern, surface ratio and rubber composition.  This evaluation method helps maintain a high performance standard while evolving designs and materials.

Nike designers must factor in a wide range of court surfaces from elite pro courts engineered with high-polished maple hardwood, to dusty composite rubber courts sometimes found in elementary schools, to the rugged blacktop found on outdoor courts around the world.

Once the differences of each court surface are studied, Nike designers determine the best traction solution for each shoe as part of the four-step approach.  A shoe like the Nike Zoom Hyperfuse Low designed for outdoor basketball in China will have a design pattern, surface ratio and rubber composition that varies from a shoe such as the Nike Hyperposite II, designed primarily for big players competing indoors in the wintertime.  Details matter.

The Nike Air Raid’s proclamation, “for outdoor use only,” literally embedded into the outsole, was a tongue-in-cheek take on the obsession for outdoor basketball played on pavement and blacktop during the early 1990s.  Designers Tinker Hatfield and Mark Smith closely studied outdoor hoops in New York City to gauge the demands of the varying outdoor court surfaces — from blacktop, to pavement to everything in between.

In his 23 years at Nike, designer Eric Avar can’t emphasize enough how important the traditional herringbone pattern has been to basketball footwear outsole design.  The herringbone pattern responds extremely well to the multidirectional footwork in basketball.  In its basic form, herringbone-patterned traction is optimal for the footwork biomechanics of the game.

There’s a steady balance of style and function that must be considered in any outsole design pattern.  Many basketball signature shoes dating back to the mid-1980s incorporate intricate designs that serve as both innovation and inspiration for the respective athlete.  The Air Jordan IX, released in 1993, featured intricate inspirations, dates and symbols meaningful to Michael Jordan, telling a story while serving a performance function.

Designer Leo Chang developed Kyrie Irving’s first signature shoe, the KYRIE 1, with Irving’s hypnotic footwork being top of mind.  Chang had never before seen an athlete contort at such extreme angles when accelerating, cutting and crossing over.  Irving’s movement led to Chang’s KYRIE 1 outsole design, which features sidewalls wrapping up the shoe with a modified herringbone pattern throughout the entire outsole for maximum grip intended to prevent slippage.  The performance benefit was infused with inspiration: Irving’s favorite motto, “Hungry and Humble,” comes to life with a letter H embedded into both the left and right outsoles.

Experts say half of a shoe’s outsole surface area should remain in contact with the court at any given time.  When designing and evaluating a shoe’s traction pattern and its contact with the court surface, it’s important to factor in three elements: impact, biomechanics and multidirectional movement.

All movements are evaluated in the design process.  For instance, while accelerating, the front third of a shoe’s outsole may be in contact with the court with the midfoot and heel off court.  With this movement in mind, pinpoint precision for each region of the outsole must be factored in while looking at the ratio of contact between the rubber and court.

In 30 years of biomechanics research at Nike’s sport research lab, senior researcher Gordon Valiant has become a resident expert in traction.  Biomechanics was in its infancy when Valiant began at Nike, but in the decades since, the lab’s role in identifying and understanding athletes’ precise movements is now essential.

The iconic 1980s Air Force 1 and Dunk designs both used concentric circles at the forefoot to allow basketball players to pivot and rotate while maintaining grip.  Current research revealed that while the early design was effective, the herringbone pattern provides optimal traction.  Creative takes on herringbone are used today in top-performing basketball shoe outsoles including the KD7, KYRIE 1 and KOBE 9.

Before it can be utilized in a shoe’s outsole, rubber must be heated to an exact temperature over a precise amount of time.  This baking process dictates the rubber’s composition and “touch,” or firmness.  The longer it’s heated, the harder the material.  The tacky grip of an outsole can be adjusted by the rubber’s composition — its basic molecular structure — and the duration it is heated.

Rubber composition and traction pattern studies available to designers have evolved dramatically over the years.  A variety of outsole types now exist: translucent, outdoor (XDR), multicolor and traditional.  Each possesses unique properties that must be considered as they are refined for a specific shoe.

At Nike, everything starts with listening to the voice of the athlete.  Signature athletes in basketball have recently commented on how the evolution of Nike’s traction has helped boost their game.

Nike Basketball’s focus on perfecting traction will continue to improve performance footwear, allowing athletes to perform at their best.  Expect to see the latest in traction design in the months to come.