Nike's new LunarEpic Flyknit is like nothing else you'll find on the wall at your local running shop. The company's now-familiar knit upper extends up over the ankle bone, giving off more soccer-cleat vibe than marathon-distance comfort. But we were able to take it for a spin at Nike's NYC studio and found it surprisingly comfortable and smooth. Here's what you need to know about this new shoe.
Flyknit continues its evolution.
Nike first released a knit shoe in 2012 — a snug racer that didn't really have a lot of stretch or conformation. But this new shoe has a mix of structure where you need it (tightly woven sections in the midfoot secure your foot in place), while constructed to allow the material to stretch where necessary (like where the shoe's collar would typically be, so your foot can flex at the ankle). Stretchy panels have been engineered into the upper not only at the front of your ankle, but also over the inner and outer bony points of the ankle, so the shoe better hugs the contours of your lower leg without irritation.
The cuff disappears.
When you first slip the shoe on, you notice it — especially if you typically wear no-show-length socks. The knit is certainly snug around your ankle, but not constrictive. We've been running on a bum Achilles for a while, and the pressure didn't bother it a bit. And, best of all, the cuff really does disappear as you begin running, just as Nike claims. We found the feel to be very much like an older, thick pair of SmartWool socks we often wear when trail running. But, why the cuff in the first place? Nike reports that it increases the surface area of the upper to reduce pressure points. In our experience with the shoe, it eliminates all of the excess material you'd usually find finishing a shoe's collar around the top opening. Instead, the new cuff stretches and flexes along with the rest of the material surrounding your heel to keep the shoe from slipping.
The shoe is plush and soft.
This doesn't come as much of a surprise when you look at the profile of the midsole and see all that white foam. But underneath the hood is a slab of lightweight Lunarlon foam that delivers excellent cushioning while also feeling responsive — you don't get that squishy feeling you often experience with other thick-bottomed shoes. The top of the Lunarlon foam is also curved, so your foot sits down into the foam. But make no mistake, this is no maximalist shoe for aging runners and recovery days, because…
It's buttery smooth.
Our test run was on a Woodway treadmill, which is the closest approximation of real-world running you'll find inside a gym. The slats that make up its belt don't bounce, which means you'll feel some jarring if you run in thin or overly firm shoes. But the LunarEpic was compliant from the moment our heel hit the belt until the toes came back off. A lot of that is attributable to the "sipes" cut into the side of the midsole and the bottom of the sole. These thin grooves are formed when foam is sliced away using a laser, allowing the remaining foam to compress a bit more easily the moment it makes contact with the ground. That same construction is used under the foot, where four rounded pods in the forefoot and one under the heel resemble a topographical map, complete with the contour lines that illustrate elevation change. This pod-and-sipe build lets the shoe bend and flex more easily as you roll forward, eliminating any slappy feeling. It also improves traction greatly because you have so many small edges making contact with the roadway (car tires are often siped for better handling in nasty weather).
Hooray for less glue.
While the ankle cuff and sole siping will get the lion's share of the attention, another excellent innovation is the marriage of the soft Lunarlon foam with the more durable white "carrier" that surrounds it. Traditionally, glue would be required to join the two pieces — just as it is to tack rubber patches to the bottom of traditional running shoes. The problem with glue is that the more you add, the more you change the shoe's ride characteristics — the cushioning gets harder, the flexibility is reduced. Glue, while generally necessary, is kind of evil. Nike, however, used a dual-injection process, where the individual parts are molded and fused together using heat and pressure. That helps the shoe remain soft and flexible, without impacting its weight (the shoe weighs 8.3 ounces for a men's size 10).
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