Testing Methodology

We’re currently on lab testing methodology 1.4.

When we test shoes in our lab, we follow a standard testing methodology to make sure that lab data is comparable across all shoe reviews. On this page, you’ll find our current lab testing methodology along with all changes that we make to our methodology as we evolve and improve our process. 

We dissect, cut, and tear shoes apart in our lab tests because minute details are what separates great shoes from the rest, and it’s our mission to help consumers buy the best shoes for their needs which requires us to know the details no matter how small. 

Weight measurements

We weigh the whole shoe before any test runs. Most of our users are from the US, where ounces are used. However, a portion are from countries that use the metric system, so we report on both the weight in grams and ounces. Our scale is accurate to 1g/0.05ounce. 

Width measurements

We measure the width of the base of the shoe at its widest point in the forefoot and the heel. We use an 8’’ outside caliper accurate to .1mm.

We also measure the width of the upper where it attaches to the midsole in both the forefoot and the heel. Again at its widest points. 

Stack heights and heel drop

To get the appropriate stack and drop measurements we cut the shoe in half and first measure the internal length of the shoe.

We flatten the shoe out to avoid any rocker or bend and measure from where the stroble board meets the heel and begins to curve upwards into the heel counter, to the inside edge of the toe bumper. We use an electronic digital caliper accurate to .01mm.

From this overall length measurement, we take the stack measurement of the heel at 12% of the total overall length, and the forefoot measurement at 75% of the total length measured again from where the stroble board meets the heel and begins to curve upwards. 

This is in accordance with how and where World Athletics measures stack heights in running shoes for eligibility requirements. 

We take all stack measurements with the insole included regardless if the insole is removable or not. 

Drop measurements are a simple calculation of heel stack minus forefoot stack. 

Insole thickness

We remove the insole and measure the thickness in the center of the heel and note if it’s removable or not.

Tongue thickness and gussets

We measure the thickness of the thickest part of the tongue. 

We also note if and how it’s gusseted to the shoe. Gusset options include

  • None
  • 1 side
  • Both Sides (fully-gusseted)
  • Both sides (semi-gusseted)

Outsole thickness

The outsole is measured in a few ways. With the shoe cut in half we measure the thickness of the outsole in the forefoot and heel, as well as the thickness of any lugs that may be present (for example on trail shoes).

The measurement of any lug is from the base of the lug to the outermost edge of the lug and does not include the thickness of the base outsole.

Outsole hardness

We also measure the hardness of the outsole material with an HC durometer at room temperature.

Midsole hardness

We measure the hardness of the midsole foam with an HA durometer at room temperature in the heel of the shoe, and if there are dual-density foams we measure those hardnesses as well. 

We also place the shoe in a 0-degree Fahrenheit freezer for 20 minutes and measure the hardness of the foam a second time to simulate cold-weather performance. 

Heel Stiffness

Heel stiffness is measured on a subjective 1-5 scale with 5 being the stiffest by squeezing the sides of the heel counter and pushing from the back of the heel counter. 

Shoe flexibility

Using a digital force gauge we measure the resistance it takes for a shoe to bend at its natural bending point starting from 0 degrees and bending it all the way to 90 degrees. Most resistance will typically be found around 20 to 30 degrees.

We clamp the shoes to a workbench with a piece of wood over the natural breaking point where the forefoot is designed to bend naturally. Once clamped down we find the center point under the back heel, 1cm from the edge of the outsole.  

The force gauge measures the maximum resistance in Newtons which is the number that we report on. 

We make 3-5 measurements unless we find outliers in our data, in which case we make more measurements to get a reasonable finding. We use an average of the measurements.

Torsional Flex 

On top of testing the flex of a shoe in the lab, we also test the shoe for torsional and longitudinal flex on a subjective 1-5 scale with 5 being the stiffest. 

Lace stretch and slip

We remove the laces from the shoe to test two factors. 

Lace stretch is quantified on a subjective 1-5 scale with 5 being the most stretchy simply by pulling the laces from end to end. 

We also test the laces for slippage using our digital force gauge. We tie a loop knot in the lace and hang it vertically. From there we tie a basic “test knot” and tighten it with the forge gauge to 100N. We have another loop knot tied at the bottom end of the lace which we pull downward on until the “test knot” slips untied. We record the max effort taken to untie the knot. 

Heel tab type

We note if the shoe has a heel tab. Options include:

  • Finger loop
  • Pull tab
  • None

Breathability

Breathability is measured on a subjective 1-5 scale with 5 being the most breathable by filling the shoe with smoke created by dry ice and boiling water. 

Each shoe is filled with smoke using approximately 1 cup of dry ice chunks in a bowl filled with 2 cups of boiling water. The smoke is pushed through the shoe using a cooling fan. 

This is filmed in slow motion at 240fps and analyzed for scoring.

In-depth review methodology

We have built a team of trusted athletes who are:

  1. passionate about their sport
  2. know what makes the best footwear for their activity

The goal is to provide you with the first-hand experience of each shoe’s feel, fit, and performance, coming straight from the trail, track, gym, or court.

About our testers

We are partnering with 100+ athletes to cover 16 sports shoe categories. Each reviewer comes with a strong background in their respective sport.

Here is the track record of our testers in the Running category:

  • run at least 30 to 40 miles a week, with some going up to 70 miles a week when training for a marathon
  • be a competitive runner on various distances (from 5K to ultra)
  • do all types of runs, from easy days and long hauls to fartleks and speed training
  • face various terrains and weather conditions
  • set PRs (some of the examples include 15:57 for a 5K and 3:28 for a marathon)

Learn more about our testers from other categories here.

What makes our reviews different

1. We buy all tested shoes with our own money

Our testers receive no free shoes from the brands. This is to avoid brand loyalty and bias. They are free to express their honest opinions.

2. We focus on what we experience, not shoe features

Most shoe reviews follow a standard pattern: outsole, midsole, upper. They describe technical details about each component leaving out the shoe’s performance as a whole. Our reviews are made to help you “feel” the shoe as if you were trying it on for real.

Our in-depth review process

We make sure that the most valuable information comes first. That’s why the top three sections in each review cover the following:

  • how the shoe was tested
  • who should (NOT) buy it
  • pros and cons

Our research shows that these are the most-searched-for aspects of a shoe review. 

How the shoe was tested

The type of activity, its duration, terrain/surface, and other nuances are all included in this part. It will help you understand the context of the shoe’s performance.

Who should (NOT) buy it

Here you will learn about the best uses for each shoe and whether it’s not recommended for certain purposes. If the shoe is limited in some aspects, we always suggest alternatives to help in your search.

Pros and cons

This section provides a quick, scannable overview of what our tester thinks about the shoe. Each bullet is further explained in the corresponding sections.

Other review sections

The other sections include information about the shoe’s fit, comfort, weight, durability, breathability, among many other aspects. These largely depend on the category and what is important to that particular activity.

Each section is followed by a photo or video which helps to illustrate the tester’s experience.

Meta review methodology

Unfortunately, our current team cannot test every single shoe just yet. However, it is still our goal to cover all shoes on the market. That’s what the meta reviews are for.

Which opinions we include

For the shoes that we haven’t got a hold of ourselves, we make a summary of all available reviews for each model. So far, we have read over 7 million reviews for 9000+ shoes from 16 different sports categories.

We include opinions from expert shoe reviewers, athletes, and regular purchasers to understand various perspectives better:

Expert reviewers/bloggers can be biased due to their partnerships with brands; however, they provide more nuances about footwear than any other group;

Athletes may not have extensive knowledge of footwear but they can test shoes in rigorous, real-world conditions;

Regular buyers may lack a background in sports or shoes but usually provide honest opinions about the shoe’s comfort, value, and durability.

We do NOT include the opinions of our own writers in meta reviews.

How we summarize

To save your time, we spend at least 7 hours per shoe, summarizing the opinions of everyone who has reviewed it.

The result is a concise, scannable overview of reasons to buy and not to buy the shoe. A short snippet at the top of the page also helps you understand what the shoe is all about.

Below are the key principles we follow:

1. Avoid vague statements.

Instead of stating “this shoe is durable” we dig for the nuances: “After 50 miles on country roads (gravel, hills, and a bit of mud), the midsole is still intact and is not packing out. The outsole, meanwhile, also has zero signs of wear.”

2. Use clear language, no jargon or terminology.

Our main goal is to provide information, not to sound smart. That’s why we describe shoe technologies in the most simple, accessible way.

3. No sugarcoating.

If the shoe received primarily negative feedback, we make it clear in our verdict. We challenge the brand’s marketing statements if the shoe doesn’t live up to the expectations.