The Zoom KD 9 marks my rather late introduction to Durant’s signature line. Does its new take on Nike’s much loved Zoom Air make it worth the wait?
Longtime visitors to this site will know that it used to be focused exclusively on performance-based reviews of basketball footwear. During its heyday through the early 2000s, Kicksology.net attracted more visitors than either NikeBasketball.com or Rbk.com—not too shabby for an endeavor started for fun in the non-existent free time I had while co-managing a Web start-up.
This notoriety was both exciting and unexpected, but, unfortunately, before too long, it also started to become very expensive. You have to remember that this was in the era before turn-key Web hosting with infinite bandwidth; the site was transferring gigs of data per month and I was paying by the bit. Thanks to Google’s AdSense platform I was able to break even and occasionally turn a profit, but that was without taking into account the tens of hours spent per week writing reviews, snapping and editing photos, and maintaining my virtual server.
By late 2004, I had reached the point where I needed to make a decision: Dedicate myself full-time to growing Kicksology.net into a sustainable business, or shut it down so that I could reclaim my life and pursue other interests. Long story short, I chose the latter, and, with the benefit of hindsight, it’s clear that it was the right call.
figure 1. The Zoom KD 9 is surprisingly restrained in its application of overt athlete branding, with this KD logo at the heel representing the only easily visible callout to the shoe’s namesake (the iD version shown here is a stealthy black-on-black, but most inline colorways “pop” the KD logo to make it more visible). But, as highlighted in this excellent interview with the shoe’s designer, Leo Chang, the shoe is rife with more subtle cues. For example, “the texture on the heel, it’s actually inspired by the texture on a handgrip from a camera, because [Durant’s] gotten really into photography.” The shoe’s performance is also deeply informed by Durant’s unique needs, as noted below in the section regarding the shaping of the KD 9’s all-new Zoom Air platform.
The reason for this history lesson is to explain why it is that the 9 is the first shoe in Kevin Durant’s signature line that I’ve purchased and played in. You see, after shuttering Kicksology.net, I was very much “on the wagon” when it came to kicks. I gave away all but a handful of the 1,500-plus pairs of shoes that I had amassed during my four years running the site, and promised myself—and my wife—that I’d only buy new sneakers when I really and truly needed them (what a novel concept!).
And I held true to this promise, even during my stint as a product manager in Nike’s Running Footwear category starting in 2007. That was akin to an alcoholic working in a whiskey distillery and somehow managing to steer clear of the hooch, which was only possible because I was so damn busy learning what exactly it meant to be a product manager.
It just so happened that 2007 was the same year that a certain Kevin Durant entered the NBA, with his first true Nike signature model debuting in 2008. Since this period coincided with my self-imposed exile from sneaker-dom, I completely slept on it. And my somnambulance continued through the entirety of Durant’s career in Oklahoma City. I never even tried on a pair of KDs, let alone purchased a pair, until the 9s opened my eyes and convinced me that it was time to open my wallet.
figure 2. Here’s the shoe that knocked me off the sneakerholic wagon, the stunning Kobe 9 Elite. It’s shown here as a low, but its ultra-high-top execution is the defining version of the model.
Truth be told, the shoe that knocked me off the sneaker-holic wagon was the Kobe 9 Elite that hit the market in early 2014. Representing the first-ever application of Flyknit in hoops and featuring a sublime design penned by the legendary Eric Avar, that shoe absolutely shattered my willpower. Still, while I’ve since relaxed my ban on non-essential kicks, a decade of abstinence has shown me that I can do without. So I’ve approached new buys with a much more discerning eye, limiting pick-ups to shoes that strike me as special, perhaps due to an iconic design (e.g. the aforementioned Kobe 9), or because they mark an important milestone (e.g. the Kobe XI), or because they meaningfully advance the state of the art in on-court performance.
When I saw the Zoom KD 9 and its entirely new full-length Zoom Air platform, I thought it had the potential to fall into that last bucket, and a few weeks with the shoe confirmed that assessment. Is it worth the $195 bones I put down for a customized pair via NIKEiD? Value is a difficult thing to quantify given its innate subjectivity, but I can tell you that the KD 9 is the best performing basketball shoe I’ve played in over the past two years—a comparison that includes the significantly more expensive Kobe XI Elite. Since I’m out of the shoe review business, check out KickGenius, Schwollo.com or WearTesters.com if you’re looking for on-court assessments. And, while you’re at it, definitely give Nick DePaula’s excellent in-depth backgrounders a read to learn more about the genesis of the KD 9. His coverage of the shoe includes a terrifically candid interview with Leo Chang, the designer of every KD to date, as well as an extended conversation with Durant himself. The latter touches on a range of topics, including the pricing of the KD line, and I found Durant’s direct response on that point to be a breath of fresh air in an age when star athletes are about as forthright as politicians in an election year.
So, this isn’t a performance review, but, for the benefit of those with a keen interest in the technical aspects of contemporary kicks, I thought it worthwhile to take a closer look at the feature of the KD 9 that most sets it apart as a performance shoe. As its full name suggests, the Zoom KD 9 is built on Nike’s Zoom Air, which is a variant of the company’s iconic Nike Air cushioning platform. Many of you will already know this, but what sets a Zoom Air unit apart is that it’s reinforced by an internal matrix of very strong synthetic fibers. Those fibers are lined up in rows like soldiers in formation and, in the case of the KD 9, those rows are visible through the shoe’s clear midsole sidewalls (see figure 3 below).
figure 3. In this profile view of the Zoom KD 9, the rows of synthetic fibers that hold its pressurized Zoom Air unit together are clearly visible. Also visible is the deep forefoot groove that contributes to the KD 9’s terrifically smooth, natural feel underfoot. In my experience, this is the best execution of Zoom Air that Nike’s ever offered in a basketball shoe, and I hope we’ll see more of this configuration in other hoops models.
The fibers hold the top and bottom of the air bag together, which does two very important things. First, it enables the creation of an Air-Sole with flat, completely uniform top and bottom surfaces that, unlike the rounded, balloon-like topology of a Max Air unit, doesn’t require a moderating layer of foam to be stacked on top of it. This, in turn, allows for a lower-profile, more inherently stable platform underfoot. Second, the combination of the nitrogen pressure within the bag pushing out and the synthetic fibers pulling in makes the overall system work like a compression spring, storing energy on impact and returning far more of it back to the wearer than conventional midsole foams or even Max Air. It’s this combination of low-profile stability and trampoline-like springiness that’s made Zoom Air such a hit with ballers.
The thing is, precisely how much of that springiness you can actually feel is very much subject to the way Zoom Air is implemented in a given shoe. Taking my Swoosh hat off and speaking purely as an outside observer, I’d have to say that, in too many of Nike’s recent hoops offerings featuring Zoom, that springiness is MIA. In some cases you might start to feel it after multiple wearings, as the surrounding foam breaks down; or you might feel it if so long as you weigh in excess of 200 pounds. But the bottom line is that a Zoom Air logo on the midsole is a promise that Nike doesn’t always deliver on.
If you’ve felt let down by Zoom Air in recent years and have joined the ranks of lapsed adherents to the technology, the KD 9 may well rekindle a spiritual awakening. Its implementation of Zoom is the best I’ve ever experienced—better than the OG Air Jordan XIV, which has been my benchmark for Zoom-based cushioning since its release nearly two decades ago. What makes the KD 9’s cushioning so great, you ask? Allow me to explain…
figure 4. These cutaway images of the Zoom KD 9 (left) and LeBron XIII Low (right) from Fastpass.cn aren’t controlled for scale or the angle of the photos, so they can’t be used for a direct comparison of midsole heights between the two shoes. But they’re instructive nonetheless in that they reveal the flat, uniform top and bottom surfaces characteristic of Nike’s Zoom Air vs. the rounded, irregular topology of a Max Air unit. The latter must be topped by a moderating layer of foam to be made wearable, invariably resulting in a taller, less inherently stable—but also more cushioned—underfoot platform. The greater cushioning afforded by Max could be worth the trade-off for bigger, heavier players, but I’ve always preferred the lower profile feel of Zoom. As an aside, note the pronounced hump of foam added atop the midfoot region of the KD 9. This sits right behind the metatarsal heads, supporting the foot’s transverse arch, which is the arch that spans the width of the foot. This might seem like an inconsequential detail, but I absolutely loved this feature of the KD 9 and believe it meaningfully contributes to the shoe’s overall comfort and performance.
First, is the fact that even non-heavyweights like me—I tip the scales at 172 lbs/78 kg—can actually feel its springiness right out of the box. This is largely a function of the capacious volume of the KD 9’s full-length Zoom Air unit: Because it’s so big, there’s room for the nitrogen gas inside the bag to displace on impact, then spring back as your weight shifts. It may appear that there’s a thick slab of foam stacked on top of the Zoom, but that foam only wraps up around the perimeter of the midsole to provide lateral support and stability. Cushioning directly under the forefoot and heel is delivered almost exclusively by way of the Zoom Air unit, as you can see in figure 4 above.
It’s worth noting that, while the KD 9’s Zoom Air unit is big, it’s not the biggest Zoom Air unit that Nike’s ever offered in a hoops shoe. That distinction belongs to the Zoom 360 unit that debuted in the Lebron X way back in 2012, and re-appeared in the KD VI Elite in 2014. We’re often led to believe that more is better, but, in KD’s case, that oversized Zoom 360 unit made the KD VI Elite feel “way too stiff and clunky.”
This is where the KD 9’s new full-length Zoom Air unit really shines: It holds a significantly higher volume of nitrogen gas than Nike’s standard Zoom bags, but still manages to provide a smoother, more natural feel underfoot than any previous full-length Max or Zoom Air-based shoe I’ve worn. This is in large part due to the ultra-deep forefoot groove that allows the shoe’s midsole to flex with ease under the toes. In fact, the Zoom Air chamber under the toes is all but separated from the body of the shoe; it’s only linked to the larger Zoom Air chamber by way of a very small tube (see figure 5 below).
figure 5. I didn’t have a chance to mention this in the main story, but the Zoom KD 9 provides exceptional traction. It seems like such a basic thing, but so many high-end basketball shoes fall short in this critical area. This outsole shot also reveals the small tube that links the primary Zoom chamber to the smaller chamber under the toes. This link is important because it allows the nitrogen gas captured within the Zoom unit to flow from one chamber to the next, contributing to the KD 9’s perceptible springiness underfoot, and also giving its midsole a more uniform, consistent feel from heel to toe compared to shoes featuring smaller, discrete Zoom Air units (i.e. separate units under the heel and forefoot). The downside to this design is that the tube represents a single point of failure that can compromise the entire Zoom Air unit, and I’ve seen numerous reports of Zoom bag decompression failures on the KD 9 after repeated wearings. See the section below to learn how to get a refund if this happens to you.
Although this link is small, it’s important because it allows the nitrogen within the Zoom unit to flow from one chamber to the next, contributing to the perceptible springiness highlighted above and giving the entire midsole a more uniform, consistent feel from heel to toe. The only downside to this configuration is that the small tube between the two chambers represents a potential failure point, and I’ve seen a number of posts on message boards reporting that the tube can indeed break after repeated wearings, resulting in complete decompression of the Zoom Air unit. If this gives you pause, just make sure to buy the KD 9 from an authorized Nike retailer and save your receipt. Should the Zoom Air unit in your pair fail, Nike will take back the shoes so long as they’re within two years of their manufacturing date. Note, though, that this is at Nike’s discretion—if it appears that the failure was due to normal wear-and-tear or tampering, they won’t authorize a refund. See Nike’s footwear return guidelines for the nitty-gritty.
Now, I noted above that the KD 9’s uniquely smooth, natural ride is due in large part to its deep forefoot groove, but that’s not the only factor. Also playing a key role is the shaping of the primary Zoom Air chamber—the one that extends from the heel to the forefoot. Look at the bottom of the KD 9 and you’ll see that that chamber gets very narrow at its mid point, with a significant chunk of the Zoom bag sculpted away under the medial arch. According to the shoe’s designer, Leo Chang, this was based on the specific way Durant began to apply force into the ground after suffering a Jones fracture in 2014. As Chang relayed to DePaula in the interview cited above, “In the midfoot, where [Durant] had the Jones fracture, he actually has a lot of pressure there. We shifted the silhouette of the outsole ... on the lateral side to help give him more cushioning.”
figure 6. Here’s the view of the Zoom KD 9 that you’ll get when it’s on your feet. The front half of the shoe is constructed of Flyknit that’s reinforced with webbing straps (the same straps that you lace into) captured between the Flyknit and a smooth inner lining. This package is engineered to eliminate stretch, but the combination of materials is much more pliable than Nike’s previous generation of “fused” constructions, which is a good thing because I found the upper to run quite narrow through the forefoot. As someone with wide feet, this meant my first wearing wasn’t particularly comfortable, but it felt great thereafter.
In addition to providing more cushioning under the lateral, or pinky toe, side of the midfoot, this sculpting under the arch allows the KD 9’s Zoom unit to flex torsionally in a way that the KD VI Elite’s Zoom 360 bag could not. There was a time when it was believed that torsional rigidity was advantageous in a basketball shoe because it contributed to a stiffer underfoot platform that would, as the anecdotal line of reasoning went, decrease the risk of ankle sprains. Scientific research has since shown, however, that torsional stiffness, by limiting the ability of the rearfoot to rotate independently of the forefoot during cutting movements, can actually increase the risk of ankle sprains. So, not only does the KD 9’s more sculpted Zoom Air unit feel more natural underfoot, by allowing your foot to move more naturally, it may also reduce your risk of the dreaded ankle sprain.
At this point, I could get even further into the weeds, and explain how the new manufacturing process used to create the KD 9’s Zoom Air unit makes it more inherently stable than any Air-Sole before it, or how the four notches engineered into the heel of the KD 9’s Zoom bag contribute to enhanced rearfoot stability. But I think 2,000 words on the magnificence that is the KD 9’s cushioning platform is probably more than enough for most readers. See the “Buying Advice” section below for my overall thoughts on the shoe and, if you enjoy spending time in the weeds, we can keep the conversation going on Twitter @edotkim. The bottom line from my perspective is, if you’re a fan of Zoom Air-based hoops shoes, you’re going to love the Zoom KD 9. And you don’t have to go whole hog and plunk down $195 for an iD version like I did—the standard, “inline” colorways feature the same stellar cushioning platform and retail for a more accessible $150 USD.
Who’s Worn It:
Kevin Durant (F- Golden State Warriors)
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Reviewed by Ernest Kim, |
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Nike Zoom KD 9 iD
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Price: $150 base, $195 as tested Key Tech: Nike Flyknit upper (forefoot only); all-new full-length Zoom Air unit Pros: The best implementation of Zoom Air in a basketball shoe that I’ve yet to experience—an all but perfect blend of cushioning, court feel and responsiveness; unusually good support for the transverse arch; upper offers an excellent balance of comfort and lockdown, though wide-footers may find it too narrow to start; generous, squared-off toe box gives the all important big toe room to move freely; insanely great traction (at least in colorways with a solid rubber outsole—I can’t speak to the traction in versions of the KD 9 with translucent rubber) Cons: Can be challenging to get on your foot, though this does improve with wear; upper is narrow across the forefoot and offers limited adjustability for fit; allows some up-down heel slip at the rear; numerous reports of Zoom Air decompression after extended wear (see the full story for more) Buying Advice: For in-depth recommendations from a performance perspective, see the reviews from KickGenius, Schwollo.com or WearTesters.com. What I will say is that the Zoom KD 9 is the best performing basketball shoe I’ve played in over the past two years—a comparison that includes the significantly more expensive Kobe XI Elite. As an aside, the KD 9’s low-profile, relatively firm midsole and low heel-ball offset (i.e. the difference in the height of the midsole under the heel vs. the ball of the foot—the KD 9’s heel-ball offset is 6mm, which is significantly lower than the 10 - 12mm offset typical for running shoes) make it a great option for lifting and HIIT workouts as well. From a sneaker geek perspective, I think the KD 9’s all new, beautifully engineered full-length Zoom Air unit alone is worth the price of admission. $150 is a significant chunk of change, but you’re getting a lot of tech for your money. Plus, that tech is wrapped into a shoe feels great on the foot (once it’s broken in) and transitions well to off-court wear. |
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