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Nike Vaporfly 4%

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{{DISPLAYTITLE:Nike Vaporfly 4% Review}}
The Nike Vaporfly 4% is a much-hyped shoe, which is based on the shoes Nike developed for their attempt to break the 2-hour marathon. It's an expensive shoe, retailing for $250, and even at that price it's hard to find. There are rumors that Nike are restricting supplies to drive up interest. The shoe is unusual in that it has a carbon fiber plate running through the midsole. Given all the hype, I was not expecting much from the Vaporfly 4%, but there are aspects to the shoe that have really impressed me. I'd say it's a mixture of the awesome and awful, though not in quite the ways I expected.
* The shoe has remarkable cushioning for its weight, with my measurements putting it close to the top of the table. I ran with a [[Hoka Clayton]] on one foot and the Vaporfly on the other and the Clayton felt hard and dead by comparison. The Vaporfly uses a new type of foam made of Pebax, a compound that has previously been used in harder materials like Mizuno's Wave Plate. It will be interesting to see this foam in other shoes, especially something closer to a "racing flat". There is a rumored Reebok FloatRide Floatride Racer using Pebax foam, but no details, and I've reviewed the [[Reebok Floatride Run]] which uses Pebax.
* When you wear the shoe, it has an amazing amount of bounce. It's far more than you get in TPU shoes like the [[Altra Escalante]], and feels like there's a spring under your foot. It seems like the carbon fiber plate is acting more as a spring for the rear of the shoe than for toe off. This bounce is immediately obvious, even walking around, and feels different to every other shoe I've tried. Even at the end of a marathon length run the bounce is noticeable and helped me keep up the pace. (Check out my review of the carbon fiber [[VKTRY Insoles]] for comparison.)
* I couldn't detect much difference in toe off from any other shoe, which was disappointing. The forefoot is quite stiff compared with other shoes, but given the forces involved at toe off, this doesn't seem to be enough to make much difference. Of course, a tiny difference in efficiency won't be noticeable immediately, but could make quite a difference to your finish time.
=Other Breaking-2 Shoes=
Nike's highly publicized attempt to break the 2-hour marathon was documented in the National Geographic "breaking 2" (freely available on youtube.com). That failed attempt used the Nike Vaporfly Elite, a shoe you can't buy. This Vaporfly uses the same ZoomX foam and a carbon fiber plate in the midsole as the Vaporfly Elite. There is also the [[Nike Zoom Fly]] which looks superficially identical to the Vaporfly, but is radically different and vastly inferior.
=Is It Really Faster?=
A study [https://link.springer.com/article/10.1007/s40279-017-0811-2 "A Comparison of the Energetic Cost of Running in Marathon Racing Shoes"] looked at the performance of the similar prototype shoe to the Nike Vaporfly. This study included researchers working for Nike, as well as the University of Colorado, and it used a shoe that not actually the Vaporfly, so use caution in interpreting the study. The picture below gives some insight to the construction of the Vaporfly, but also suggests some differences from the prototype which appears to have a full with carbon fiber plate.
[[File:Nike Prototype.jpg|center|thumb|300px|The prototype Nike]]
The prototype was compared with the Nike Zoom Streak 6 (NS) and the Adidas adizero Adios BOOST 2 (AB). It's nice to see that they disclosed the actual shoes they compare it to. The researchers added small weights to the two Nike shoes so they were weight matched with the Adidas. A mechanical check showed that the prototype shoe was twice as well cushioned as either of the other shoes, deforming 11.9mm versus 6.1 and 5.9 mm. They prototype also had more bounce, returning 87.0% compared with 75.9% for the Adidas and 65.5% for the Steak. The study then compared the [[Running Economy]] of sixteen male high-level runners in the three different shoes. The runners have a [[VO2max|VO2max]] of ~72, which is translates to a marathon time of about 2:20. They tested them at 14 kph (6:53 min/mile), 16 kph (6:02 min/mile), and 18 kph (5:22 min/mile), all below the [[Lactate Threshold]] of the runners (4 mmol/l, which is good enough for this study.) The running economy of the prototype shoe was 4% better than either of the other two shoes, which had similar running economy. The study noted that the prototype shoe was slightly better for rear foot landing runners (~4.7%) than the forefoot landing (~3.6%).
=Update After 100 Miles=
Normally, I would give an update on a pair of running shoes once I'd put rather miles on them. However, the vapor fly as something of a reputation for fragility, so I wanted to track its progress carefully. Even after this short distance, there is some evidence of the foam midsole braking down. If you look at the profile picture below, you can see some increases in the midsole appearing, and there is a noticeable indent under the ball of my foot. On the underside of the shoe, there is only a small amount of abrasion on the exposed foam. The hard rubber outsole (the black areas) are completely unchanged, suggesting that they are surprisingly hard wearing. The grip has improved over the course of the 100 miles. The main abrasion area on the exposed foam midsole is on the outside rear edge, where I occasionally catch my heel on steep descents. It should be noted that my running biomechanics are fairly efficient, and I'm typically quite gentle on my shoes. The upper is doing fine, even where I've cut open the toe box.