If you’re in the market for running shoes, you’ll likely come across both EVA and rubber soles. So, what’s the purpose of each? Let's discuss the basics of both.
The Basics of EVA
EVA soles are typically used for the mid-sole as they are capable of providing better shock absorption. The foam compresses with usage, which makes it absorb impact and soften the blow.
It is complex but still flexible and, most importantly, light. The higher degree of flexibility of EVA is one of the main benefits of this type of sole. This allows the shoe to provide a more natural feel and more comfort for runners. EVA sole is the most popular choice for CrossFit shoes and other training shoes. EVA also provides excellent traction when it comes to running.
This is great news for runners who are looking for a solid grip when running on different terrains. On the other hand, the EVA sole doesn’t help with durability. Therefore, it’s a less popular choice for long-distance runners who typically want durable footwear.
The Basics of Rubber
Rubber is either natural material or synthetic rubber.
Rubber is formed from the sap of a rubber plant. The sap is harvested and then processed through a manufacturing process to create the shoe material. It’s then made into soles and sold to companies like Adidas and Nike.
Natural rubber is elastic, soft, and comfortable and acts as a shock absorber when worn inside the shoe. It conforms to the shape of the wearer’s foot over time and makes for a very comfortable fit. Its main drawback is that it’s not wear-resistant, meaning it does not last long. Natural rubber is often used for indoor sports shoes.
This type of rubber is relatively cheaper than natural rubber because of its wide availability. It also has better weathering characteristics and temperature resilience, making it more durable. That’s why the range is often used to manufacture athletic footwear.
Due to varying levels of innovations, different brands have different synthetic rubber soles for different purposes:
Resin Rubber is durable, waterproof, and hard on the surface compared to other types of synthetic rubber used for making shoe soles
Polyvinyl Chloride (PVC) is mainly used when making soles of safety boots because they have excellent resistance to water, oil, and heat.
Crepe Rubber is versatile and flexible used in making shoe soles. They are made from textured sheets of coagulated latex. They are ideal for summer because they offer less traction, hence might get you slipping on wet surfaces.
Polyurethane is used to make anti-slip soles. It guarantees stability and comfort, making it an ideal option for making walking shoe soles.
Gristle Rubber is robust that makes it a perfect fit to make soles for industrial footwear.
EVA Sole vs. Rubber Sole: Outsoles Matter
We all tend to use the same brand of shoes repeatedly, so it feels like the rubber soles are practically part of the shoe. But did you know that most standard running shoes have rubber outsoles made by two different methods? And these methods can make a material difference in durability and performance.
Rubber outsoles are made from natural rubber extracted from rubber trees. Rubber soles offer unmatched wear resistance along with extending the contraction stability. Trees are cut, heated, and heavily processed to create the material you find in your shoe. They are readily available and inexpensive. Natural rubber is heavier as compared to synthetic rubber hence makes the shoe feel heavier. Both natural and synthetic rubber outsoles are naturally waterproof and bendable.
On the other hand, EVA outsoles are hard and durable, with a trait that helps them resist abrasion and slipping. EVA is commonly recognized as an excellent choice for midsoles, offering perfect cushioning and shock absorption. It is light, very flexible, and has high elasticity. Plus, it can take almost any color.
When it comes to outsoles and a direct comparison to synthetic rubbers, EVA is great too. The primary downside of EVA soles is that they do not last long.
Which Is Better for Running?
EVA has been the go-to sole material for running shoes for a while now. Its cause has been championed by companies such as Nike, Adidas, and Asics. But in recent times, there has been increasing momentum to change the situation and incorporate more rubber as a sole material.
Earlier this year, competing brands ASICS and UnderArmour broke up a long-standing alliance, and ASICS adopted the change into their running shoes. ASICS stated that it was for two main reasons. The first one is that the rubber sole delivers a better energy return which is perfect for running. That is especially relevant when going for off-road races. The second reason is that the rubber sole is more durable than EVA as it holds up better over time under intensive use.
Now, this may echo concerns in the EVA vs. Rubber debate. Applying the durability argument to EVA vs. Rubber would mean applying it to the midsole. And any runner who has dealt with the wear and tears under their feet knows that EVA midsoles wear out fast. But of course, this also depends on the amount of usage.
Choose Depending on Your Need
EVA and rubber soles are the two main categories of shoe outsoles, and both have their specific benefits and uses.
EVA soles are known for their cushioning and shock absorbing properties and are usually equipped with a rubber part in the heel to provide traction. EVA also tends to be lightweight, durable, and more shock absorbent than rubber.
Rubber soles are by and large more durable than EVA while providing a bit more traction than EVA. Rubber outsoles are usually made of either natural or synthetic rubber.
They can come in variants with a harder or softer rubber layer to best suit the runner’s needs. They can also be made with reinforced heel parts or a combination of hard and soft rubber to obtain better traction.
There is no clear winner between EVA and rubber sole, as both have their strengths and uses.
Ultimately, it is up to the runner to choose which type of sole is best suited for their running experience.