Saucony Freedom ISO: The running shoe for the neutral runner

94 / 100 by Avery Smith • Level 4 expert

Saucony Freedom ISO is a lightweight performance running shoe for the neutral runner. It is one of the most versatile shoes that I have ever run in. The Freedom ISO defies categorization. It is cushioned and responsive; flexible and fast; durable and lightweight. This shoe can handle any run, from long runs to speed work, in any temperature.





The Freedom ISO has a stripped down lightweight upper that is very comfortable. When I first put on the shoe, I was surprised by how low the heel cup came up on my ankle.

It did not provide much support, but it was very comfortable after I adjusted.



Heel Collar

The heel collar is also very soft. There is a small band of flexible plastic in place of an original heel cup to provide support, however, this does not make the heel very supportive.

It merely holds the mesh heel collar in place. Due to the unstructured heel collar, you can put on and take off the shoe without untying the laces.


ISO Fit Technology

Saucony uses its ISO fit technology in this shoe, hence the name: Freedom ISO. ISO fit technology consists of an inner sock like bootie, and an external cage of fingers that hold the laces. This gives the fit of the shoe the ultimate adaptability.

The ISO fit technology gives the shoe a very secure fit. My feet never slipped in the shoe. Any shape foot can get a secure lockdown because of the ISO fit technology.

The tongue is part of the inner bootie. It is extremely thin. The tongue and the bootie are made from the same material except that the middle of the tongue has a thin plastic reinforcement so that the laces do not bother your foot when they are firmly pressing against the tongue.




The laces are good flat laces that distribute the pressure on the top of the foot well. They do not fray easily. Two pairs of laces came with my pair of Freedom ISOs. I received a pair of matching blue laces and a pair of yellow laces.


Forefoot & Toebox

The upper material is very soft and somewhat stretchy. The forefoot was a little bit wide.

This toebox is no Altra, but it is wide for a standard running shoe. The toe box has a slight curve on the big toe side. Usually this is a problem, however, the material is so soft and stretchy that it did not bother my foot.


Heel Area

In the heel area, there is a liner of Saucony’s Run Dry material. This is a soft synthetic wicking material. It wicks sweat from your foot very well. It does not keep your feet dry in the rain.

There is a thin plastic reinforcement around the toe bumper to add structure. This did not prove to be very durable when used in the gym. There are two lines of worn away material on both of my shoes. There is also a small toe bumper of crystal rubber to add structure and protect your foot.


Upper's Breathability

The shoe has a very thin, perforated upper. A good way to test the breathability of a shoe is to put the upper next to your mouth and literally breath through it. My breathing was unobstructed, proving just how breathable the upper is.

With great breathability comes great susceptibility to the elements. This shoe was not water resistant and left my feet cold when it was cold out. This is a good problem to have in my opinion. Overall, The upper is minimal but comfortable and durable.



The Freedom ISO utilizes Everun, bouncy foam similar to Adidas Boost, as the only midsole material.

Saucony has been implementing a thin layer of Everun in all of their high-end running shoes, and now they have come out with a shoe that has a full midsole of Everun!

Everrun is marketed to give you an 83% energy return. I don’t know how accurate this figure is, however, I do enjoy the bouncy and fast ride of this shoe.

The downside of Everun is the weight. Everrun is considerably denser than other foams and therefore weighs down the shoe. That being said, the shoe is still lightweight at only 9 ounces.



Everun compared to EVA

Everun is slightly firmer than Boost; Boost is excessively squishy. Everrun is not affected by temperature changes like standard EVA. The shoe will not be damaged by the cold and it will retain all cushioning properties in the cold.

This is why I like to run in the Freedom ISO in the winter. Everrun is also said to last three times longer than standard EVA. In three hundred miles in this shoe, it feels like the shoe is brand new.



The cushioning consists of a very standard sock liner, a top sole of softer Everrun and a thick layer of firmer Everrun. The Everrun in the forefoot is more firm than the Everrun in the heel.

I am a forefoot striker so this did not affect the ride of the shoe for me. There is no plastic board underneath the sock liner, which lets your foot sink into the midsole. This gives the shoe a plusher feel. This construction allows your feet to relax more. It ends up weakening the foot muscles but the comfort is worth it.

The foot sits higher in the shoe than the visible top of the midsole. This lack of sidewalls gives the shoe less support. There is a 4-millimeter heel to toe offset in this shoe. This makes the shoe better for forefoot and midfoot strikers. Since the foam is softer in the heel, the foam in the heel compresses more than the foam in the forefoot when the foot hits the ground.



This gives the experience of running in a shoe that has a drop of even less than 4 millimeters. Heel striking in such a low drop shoe makes for long ground contact times and slow transitions from heel to forefoot. The Freedom ISO is decently flexible, especially in the sideways direction.

This gives the shoe less of a racing shoe feel and more of a comfortable, daily trainer feel. There are small, square indentations on the lateral side (outside) of the midsole and small, square protrusions on the medial side (inside) of the midsole.

This allows the midsole to compress more on the lateral side than the medial side preventing a little bit of pronation. This design is pretty insignificant; Saucony probably constructed the midsole in this way purely for aesthetic purposes. Overall, This shoe feels slow and clumsy while heel striking, but fast and responsive while forefoot striking.



The Freedom ISO has a highly durable crystal rubber outsole. The Crystal rubber covers almost the entire outsole.

Crystal rubber lasts longer, is much more flexible and is more lightweight than regular carbon rubber. After 300 miles, my shoes did not show significant wear.



The problem with Crystal rubber is the traction. This rubber is not very sticky. I could not grip slick roads or snow well. The grip was considerably worse than carbon rubber or Saucony’s other rubber material: IBR. The traction was fine on groomed trails, treadmills, dry tracks and roads that aren’t super slick. The Triflex chevron pattern on the outsole adds surface area and improves flexibility. I wanted this to be the perfect winter running shoe, but it did not grip icy roads well enough.  


Who is the Freedom ISO best for?

I used the Freedom ISO for running in the winter mainly as a daily trainer on the roads and on the treadmill. The shoe is lightweight, flexible and well cushioned, which are my three requirements for a daily trainer. I used the shoe for some up-tempo running.

The Everrun responded well to the speed, however, due to the flexible design, it was not my personal favorite for speed work. I did not use the shoe on days that were too wet. The low heel and breathable upper let too much water in.

I actually wore the Freedom ISO casually sometimes. It was good looking and comfortable. I recommend this shoe to any neutral, forefoot or midfoot striker, looking for a versatile training shoe with racing potential, especially if they run in the cold.



I wear a size 12 in this shoe. This is my regular Saucony shoe size. This shoe runs ½ size larger than brooks road shoes (apart from the Ravenna which is the same size.) It fits about the same as the Brooks Cascadia and Mazama.

This shoe has the same sizing as Altra road running shoes, apart from the Instinct, which runs ½ size smaller. This shoe runs ½ size larger than most Hokas. It runs ½ size smaller than most Nikes, apart from the Lunartempo and Lunaracer, which run a full size smaller.

This shoe runs about ½ size larger than Adidas shoes. This shoe fits the same as Asics Dynaflyte, but runs a ½ size larger than Asics Gel-Nimbus. It fits ½ size larger than La Sportiva trail running shoes.




Saucony Freedom ISO vs. Saucony Kinvara 8

The Kinvara 8 is lighter and faster. It is much less durable and less comfortable. The Kinvara 8 is much less responsive than the Freedom ISO, however, while standing in the two shoes, they feel similar because they both have a full length Everrun top sole. The two shoes have the same geometry, but a different ride.


Saucony Freedom ISO vs. Brooks Launch 4

The two shoes weigh about the same amount. The Launch has a higher stack height, denser cushioning and a 10mm drop. The launch is stiffer than the Freedom. They are both very durable. The Launch is a better option for heel strikers looking for a more minimal daily trainer with racing potential. You should buy ½ size up in the Launch.


Saucony Freedom ISO vs. Hoka Clayton

The Hoka Clayton has a firmer forefoot and a softer heel, similar to the freedom ISO. The Clayton uses EVA foam as the midsole and RMAT, Hokas equivalent of Everun as the outsole. The Clayton is lighter, much, stiffer and more cushioned than the Freedom ISO. They both have a 4 mm drop. You should buy ½ size up in the Clayton.


Saucony Freedom ISO vs. Adidas Boston Boost

This is the shoe most similar to the Freedom ISO. Both shoes have a similar ride because of the similar midsole and similar flexibility levels. The Boston is heavier, softer and has a 10mm drop. This shoe is better for heel strikers. It fits ½ size smaller than the Freedom ISO.


Saucony Freedom ISO vs. Saucony Zealot ISO 2

The Zealot ISO 2 is Saucony’s plush cushioned shoe for the forefoot striker. The Freedom ISO has a much more comfortable fit. The upper on the Zealot is Narrow and coarse. The Freedom has less cushion, is more responsive and is a little bit lighter. They both have a 4mm drop. The Zealot ISO 2 fits ½ size smaller.



  • I take off 4 points for the traction
  • 1 point for the weight
  • 1 point for the cuts in the toecap



Overall, this was one of the best shoes that I have tested. It has a very comfortable upper and a fun, bouncy ride. At 160 dollars, the Freedom ISO is very expensive. In my opinion, it is worth the extra cost.

This shoe will last much longer than other shoes and is extremely versatile. You can do anything from long runs to 400-meter repeats at any temperature. This is the perfect choice for forefoot and midfoot strikers looking for a responsive and cushioned road running shoe.                           

Avery Smith

Avery Smith • Level 4 expert

Avery Smith is a student at a school in Western Massachusetts. He spends his breaks in the rocky mountains with his family. Avery runs every distance, from short track races to ultra marathons. He has come in the top three in his age group for every ultramarathon that he has raced.

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Saucony Freedom ISO