Explanation and guide to choosing an outsole

The outsole is among the most important parameters when buying running shoes.

Your choice of sole should reflect the surface you run on.. The smoother the terrain, the flatter the sole you need. The rougher the terrain, the rougher your outsole should be.

In this guide you will learn everything worth knowing about soles for running shoes.

“Sole” refers to the outer sole and not theinsole or insert (link to article), as they are also called.

Overview of different types of soles

Imagine that the roughness of the outsole is a scale where 0 is extremely flat and 10 is extremely rough.

I have outlined how rough your sole should be depending on the surface you run on:

• 0-2: Asphalt, sidewalks, bike paths, concrete or athletics tracks.
• 3-4: Larger compact gravel paths, hard packed soil or grass.
• 5-6: Trail running – running on small trail systems and forest floors
• 7-8: Mud Run – running in wet and muddy terrain
• 9-10: Winter running – running in snow and ice

I go through each of the different substrates.

First you will see a video where I go through examples of types of outsoles for running shoes.

Soles for running on asphalt

The typical asphalt running shoe is very flat in the sole.

You don’t need structure in your sole, as you have good grip and grip on the surface even without extra studs. The picture below shows a typical sole for running on the most compact surfaces.

The grooves in the shoe provide extra grip so you get a good start.

If this is the type of shoe you are looking for, I can recommend it to you. this article about traditional and flat running shoes with a focus on asphalt running.

Soles for running on gravel paths

If you are moving out onto the gravel paths, a bit of structure would be good. See the image below.

The shoe on the right, Salomon S-Lab Sense, is good for traditional larger gravel trails,while the shoe on the left, Inov8 Trailroc 255, is best on the slightly more uneven gravel trails.

Soles for trail running

Soles for trail running

There are many different ways to build shoes with a strong grip that are not too heavy or unwieldy. The example below is the good trail shoe Saucony Peregrine.

Note how the shoe has triangular spikes. Some shoes, such as the Inov8 Trailroc 255, which I referred to earlier, do not use the triangular spikes, but flat spikes.

They are a little less resilient. On the other hand, they are better for downhill running.

In fact, I think Peregrine can also be used partially for the next category, where things get a little muddier.

If you are into trail running and looking for new shoes, I recommend you read our Complete guide to choosing trail shoes.

Mud running soles

During periods of heavy rain and slush, it can be a good experience to train in a pair of shoes with high-profile rubber lugs. An example is the Inov8 Mudclaw, which you see below.

The downside of shoes like these is that if you run on more compact surfaces, the studs wear out quickly.

It’s fine to run a few hundred kilometers on asphalt before you enter the forest, but several kilometers on asphalt is not recommended.

Soles for winter use

As winter approaches, you should consider iron spikes for your running shoes. You generally have 2 options:

1. Use your normal running shoes and strap on extra winter shoes with iron spikes. The advantage is that you don’t need an extra pair of shoes just for running in ice and snow.
2. Buy an extra pair of shoes. It will give you a better running experience.

Whether you choose 1 or 2, I won’t be the judge. It’s inconvenient to have an extra pair of shoes for running in snow and ice if you only use the shoes 5 times during a year.

If you are going to run in the winter, I recommend you read The guide to choosing winter running shoes.

The picture below shows how snow and ice settle on two shoes. The bottom shoe has iron spikes.

Difference between the sole for trail running / loose gravel and the sole for asphalt running / hard packed gravel

Here you can see an example of a shoe that is good for everything from level 1-4 on my scale (the shoe on the right), while the shoe on the left is best suited for terrain around 4-7.

A concluding comment

The vast majority of running shoes sold are in the 0-2 category – i.e. for running on asphalt and other hard surfaces.

I think there is too little focus on the choice of outsole. If you run trail races, you will love a rougher sole.

I hope you found the guide to choosing an outsole useful. Maybe you know someone who would also like to read the article?