Nike categorizes a shoe by three basic components. Upper, Midsole & Outsole. Nike also thinks the best way to think about this concept is by referencing a Car. For example- Upper = Body Of Car / Midsole = Suspension Of Car / Outsole = Tires Of Car. In this particular article though I will be writing about Midsoles only.
The Midsole is the layer that is in between the Upper & Outsole of the sneaker. It is the MOST IMPORTANT part of the shoe due to the fact that it provides Stability, Cushioning & Shock Absorption. Also the Midsole usually incorporates some type of Nike Cushioning Technology as well to work together to provide the best cushioning available & protect the foot but that's a topic for another Article.
Here I will be breaking down Midsole "Materials"
EVA AKA Ethylene Vinyl Acetate
EVA is the least expensive midsole material & is commonly found in entry level shoes (Think Nike Benassi Swoosh Slides, those are EVA). The reason it's so inexpensive to make is because the Midsole is cut & shaped directly from flat sheets of EVA Foam. So while the PRO for Nike would be it doesn't cost them must to make, the CON would be EVA compresses & becomes flat over time due to the air trapped within the foam being squeezed out. Once the EVA Foam is compressed, it will never return to its original shape & it will no longer provide cushioning unfortunately. To add to the downside EVA Foam compresses faster then ANY OTHER Midsole Material.
So Phylon happens to be the GO TO Midsole material when it comes to the options Nike has in it's stable. Reason being is it's lightweight, low profile & responsive. Phylon is made of EVA Foam Pellets that are compressed then heat expanded & then finally cooled into a mold. This compression molded foam is sculpted into a variety of designs to accommodate the designers idea (think Nike Penny 1). Most people know Phylon is easy to identify by the fine wrinkles the foam shows after usage.
PU AKA Polyurethane
PU is the HEAVIEST Midsole Material that Nike has available. It is the MOST Dense, Durable & Stable Midsole Material as well. Polyurethane is poured in to a mold to create a firm midsole that provides maximum protection from impact. PU is pretty easy to identify by it's smooth rubbery feel, not to mention it tends to turn yellow with age (think Nike Air Max 1, 90, 95, ETC).
Phylite fuctions as both a Midsole & Outsole. By fuctioning as both the weight of the sneanker is GREATLY REDUCED (obviouly because the sneaker no longer has the heavy Rubber Outsole Material) & flexibility increases. Phylite is a Injection Molded Unit made of a combination of 60% Phylon & 40% Rubber, making it Lighter then Rubber BUT Heavier then Phylon. For the most part Nike does add BRS 1000 in High Wear Areas on Phylite once in a while to increase Durability (Think Nike Free. They usally have it on the Toe & Heel).
Not much is to be said bout this Midsole material due to the fact Nike doesn't use it as much. It can be found in the Running Category in shoes like the Nike Zoom Pegusus & Nike Zoom Vomero (has been used in the Basketball Category as well). Cushlon is a mix of Phylon & Rubber Additives but don't get it confused with Phylite since the Rubber Additives are very minimal in comparison. Cushlon is Lightweight, Responsive & gives a very Bouncy feel.
As much as I disagree, Nike considers Lunar Foam a Midsole Material (which makes no sense since they also consider it a Nike Technology). I am assuming they mean Lunar Foam in the Full Length setup is a Midsole Material. Lunar Foam is very difficult to explain in a paragraph but I will try my best. Lunar foam is a Hybrid of EVA & Nitril Rubber in a Nike Patented mix & process. It is 30% lighter then regular compression molded EVA & Phylon. Instead of absorbing the impact when your heel strikes the floor it actually distributes the pressure along the foam to give a more even impact across the foot. Think those Dr Scholls insole machines that let you know how much pressure you put on a certin point of your foot, with Lunar Foam those Red areas would become a Orange or Yellow color due to the Foam distrubting the impact. Another thing is Lunar foam isn't Durable another to sustain itself so it is held in a carrier. The carriers are either 1 of 2 things, Phylon or Phylite. The easiest way to imagine this is imagine the Phylite/Phylon as a Coffin, the Lunar Foam in placed inside the Coffin like a body. When Lunar Foam is placed in a Phylon Carrier it is called Lunarlon. When the Lunar Foam is placed in a Phylite Carrier it is called Lunarlite (Nike no longer uses Phylite carriers due to durability issues, so Lunarlite doesn't exist anymore technically). Also another cool thing about Lunar Foam is it actually adapts to to most Runners Gaits because of the Distributing of Pressure factor.
Here I will be breaking down Midsole "Features"
The footframe is a rasied wall around the footbed that cups & supports the foot. It keeps the foot centered over the midsole (which in turn prevents rolling your ankle) & increases stabilty. Obviously the higher the Footframe the greater the stability but the height of a Footframe varies by sport.
This is probably my favorite Midsole Feature just because it actually works. Instead of having a FLAT Platform to support your foot (Think Nike LeBron 11. I HATED HOW IT MADE THE BOTTOM OF MY FOOT FEEL SINCE IT WAS SO FLAT) a Contoured Footbed mirrors the shape of the bottom of your foot providing a anatomically correct base of support.
The Footbridge is kind of difficult to explain. It is found in the Running Category in Nikes most supportive sneakers (Think Nike Zoom Structure Traix/ Equalon). The Footbridge is a TPU device added to the medial side of the running shoe. It enhances stability & slows the Rate Of Pronation. It is made up of 2 large post at the base of the platform that REACHES UNDER THE FOOT. The posts absorb energy as the foot strikes the ground & transmits the energy across the platform, so as the energy is absorbed & the foot rolls inward to pronate it actually bumps against the 2 base posts & then energy is released & the foot moves foward. Pretty difficult to explain any other way.
Most NTers are fimilar with the Midfoot Shank due to the Air Jordan 11. The Midsole Shank is a Injection molded TPU/Carbon Fiber/Glass/ ETC. structure that is incorporated into the Midsole. It enhances Stability & provides Torsional rigidity AKA Controls Twisting Movements. Incorprating a Midsole Shank allows for Midsole Material to be sculpted away to reduce the weight of the shoe without comprimising the Stability of the sneaker. MJ also says it saved his knees if that means anything to you LOL (=).
Here I will be breaking down Midsole "Enhancements"
Interlock PU & Phylon
So Nike Incorporates 2 different types of Midsole Materials (Polyurethane & Phylon) to make a unique Midsole that provides EXCELLENT Cushioning & Stability. The Midsole is made by putting the Softer material (Phylon) in the Forefoot & the more stable material (Polyurethane) in the heel, the reason for this is because the heel of the sneaker must be able to house a Air Max Unit while still adding excess Stability. This Midsole Enhancement is usualy found in the BasketBall & Running Category.
Dual Density Phylon
Dual Density Phylon is a technique used to increase Stability on the Medial side of a running sneaker. 2 varying densities of Phylon provide a Stiff Midsole in certain areas & a Softer Midsole in others.
Hope you guys enjoy the information I provided. I will eventually add pictures to this Article to help. Feel free to add any Nike Midsole (Materials, Features & Enhancements). If you have any further questions about this Article or any Nike Tech Info at all feel free to send me a message.
sources come from Nike & myself. I was a Store EKIN in Orlando Florida For 3 Years. I was in charge of on boarding all employees in 5 Nike Outlet stores in the area. I taught the Nike W. I. N. Program (Welcome Into Nike Onboarding Program Is Required For ALL people hires by Nike. Two days of History & Heritage are required to be learned by all hired employees).
P.S.- Please Pardon All Spelling/ Grammar Errors. I Wrote This On My iPhone (this took a long time)