Options for Flat Replacement Insoles for Running Shoes: Inov-8 and Ortholite Fusion

I’m a big fan of swapping insoles around between shoes. Sometimes a shoe might fit a tad tight, and swapping in a thinner insole from another shoe can free up enough space to make the fit comfortable. Sometimes a shoe is too cushy or too firm, and an insole change can completely change the feel for the better.

A perfect example of where swapping insoles saved a shoe for me was the Newton Energy. The included insole was too thick under the heel, and my heel would not lock down properly as a result. The insole was also too soft – overkill in a shoe with an already soft midsole. Swapping out the factory insole for a thin, light alternative turned the Energy from a shoe I’d hesitate to run much in to one of my favorite shoes of 2013.

As a shoe reviewer, swapping insoles is easy for me since I have a bunch to choose from. However, I’ve been asked a number of times about where to buy a thin, flat insole to use for this purpose, and it has been surprisingly difficult to find good options. Most replacement insoles for sale are heavily structured with thick cushioning and pronounced arch support – not ideal when the goal might actually be to increase space inside a shoe. Running on a bare footbed with the insole removed is an option, but the footbed can sometimes be rough or have exposed stitching.

After a bit of digging around, and a trial offer from an insole manufacturer, I’ve come up with a few options that are decent.

Inov-8 Replacement Insoles

Inov-8 sells insoles that are completely flat, firm, and have no arch support (the insole does curl up a bit on each side, but that is to assist with placement in the shoe I think). The insoles come in two thicknesses: 3mm and 6mm. I purchase pairs of both and measure the 3mm version to be 3mm in the forefoot, 4mm in the heel. The 6mm seems to be uniform thickness at heel and forefoot. For comparative purposes, the included insole in the Saucony Mirage 4 measures about 5.5mm heel, 4mm forefoot, and that in the Brooks PureFlow 3 is a uniform 5.5mm from front to back.

The 3mm insole appears very similar to the insole in the popular Inov-8 F-Lite 195 shoe (gray insole in photo below). Shape is also similar enough to the Saucony Mirage and Brooks PureFlow insoles that they swap into those shoes without a problem.

Inov-8 Insoles

Left-to-Right: Inov-8 3mm Footbed, Inov-8 F-Lite 195 insole, Saucony Mirage 4 insole, Brooks PureFlow 3 insole, Inov-8 6mm Footbed

Inov-8 3mm 6mm Footbed Comparison

Top-to-Bottom: Inov-8 3mm Footbed, Inov-8 6mm Footbed, Saucony Mirage 4 insole, Brooks PureFlow 3 insole

The Inov-8 insoles are available for $10 at Zappos in the US. I’ve had a hard time tracking them down outside the US. Amazon UK has them (seems Amazon US does not), so you might check the Amazon shop for your country.


Ortholite Fusion Insole

If you’re looking for a relatively thin, flat insole that has a bit more cush, the Ortholite Fusion might be worth a shot (Disclosure: Ortholite sent me a free pair to try out). Ortholite makes insoles for a lot of shoes on the market, you may even have a pair yourself. It’s a much softer insole than the Inov-8 models – almost has a memory-foam like feel to it. I measure the Fusion between 4.5-5.0 mm at both the heel and forefoot (hard to get it exact since it’s really soft). In the image below they look a bit thicker than the Inov-8 6mm insole, but I think they thicken a bit along the margins where I trimmed them.

Unlike the Inov-8 footbeds, the Ortholites have a bit of soft arch support built in, but it’s not terribly obtrusive given how soft and flexible they are.

Ortholite Fusion Insole Comparison

Left-to-Right: Inov-8 6mm Footbed, Inov-8 3mm Footbed, Ortholite Fusion Insole

Ortholite Fusion Insole Comparison

Top-to-Bottom: Inov-8 3mm Footbed, Inov-8 6mm Footbed, Ortholite Fusion Insole

The Ortholite insoles do seem to have a bit more girth, and they take up a bit more space inside a shoe, but if you have a shoe that runs like a brick with the included insole they may make things a bit more runable. You also have to cut them to fit your shoes so you can remove as much material as necessary to squeeze them in. I simply used an existing insole as a template and traced around it, then cut the margins off to make the Ortholite the same size and shape.

The Ortholite Fusion insoles are available in the US for $20 per pair at Amazon via Ortholite. I’m not sure why they’ve opted to sell this way, but you have to select a size on Amazon, then click on where it says “Available from these sellers” to purchase direct from Ortholite.

Other Options

Merrell sells an insole that comes in 3 thicknesses: 7mm, 5mm, 2mm. I have not tried them myself, but seems like it might be another decent option.

I’ve been trying to get Skechers to sell their insoles separate from their shoes – I swap Skechers insoles around frequently. Some people have had bunching issues with the thinner Skechers insoles, but has not been a problem for me.

If you have any other suggestions, please share in the comments!

About Peter Larson

This post was authored by Peter Larson. Pete is a recovering academic who currently works as an exercise physiologist, running coach, and writer. He's also a father of three and a fanatical runner with a bit of a shoe obsession. In addition to writing and editing this site, he is co-author of the book Tread Lightly, and writes a personal blog called The Blogologist. Follow Pete on Twitter, Facebook, Google+, and via email.

Comments

  1. I like the look of the Inov-8 3mm insoles. That looks like a real possibility.

    I may be wrong but I think that the Merrell insoles are made by Ortholite. I have called them before and asked if they had a zero drop insole for sale and a CS rep told me that they didn’t.

    I have also called Skechers to ask them to sell me a separate replacement insole and they said that they didn’t do that.

    • They have a few different models. One is Ortholite, the one I linked is something else. No sure if any are flat or not. Quite possible the CS rep had no idea what you were talking about :)

      • Trail Running Dad says:

        I’ve got a pair of the Merrell insoles Pete linked to in the article – they’ve worked pretty well for me, and seem flat (sorry, no calipers on hand to test it!), though there’s definitely a bit of a heel cup and curve in the arch. I use them in the Merrell ProTerras, to replace the stock insoles (4 or 5mm). As I’ve got a narrower foot, I use the 7mm insoles to take up a bit more volume, and the fit is much improved.

        Only limitation is that the insoles are designed for the last of more traditional Merrell shoes – thus, the insoles are a bit narrow in the forefoot relative to the shape of the shoes in their M-Connect/Barefoot line. They’re still pretty good for me, but would be best in shoes with medium/narrow-width forefeet.

  2. Hi Pete!
    Great post and great timing for me. One question, do you know if there are any “neutral” insoles with built in 4 mm drop?

    • That would be the Skechers insole I’m trying to get them to sell! Not aware of any on the market now.

    • Hey Niklas, That’s exactly what I was looking for.

      I have some Inov8 Trailroc 235′s, but I’m not ready for zero drop shoes (although I didn’t want the 245′s or 255′s as they are too stiff and protective.)

      I couldn’t find any simple, unsupportive insoles with a 4mm drop, but in the end I found these which work pretty well:
      link to rei.com

      They give about a 4-6mm drop I guess, and a touch of arch support (although this doesn’t bother me.) Obviously they leave the forefoot without any insole at all, but I love this as it maximises ground feel.

      Hope this helps :-)

  3. i’m glad to know that i’m not the only one who’s eager to tinker with insoles once i get the shoes home!

    i’ve swapped around my skechers insoles all over the place. right now i don’t believe that i have a single pair of shoes with the original insoles in them.

  4. An old yoga mat makes great insoles.

  5. Mike Graber says:

    6 mm is one-quarter inch thick. Is the Inov-8 really that thick? That seems like a lot. The 3 mm and 6 mm insoles don’t seem that different in the pictures. ??

  6. Hi Peter,

    Have you tried using sheets of PU foam or even Poron? You can get it in various thicknesses for pretty cheap (cheaper than buying insoles…), it lasts a long time, and has a good cush feel without being too soft. We’ve even seen some performance advantages with these in testing…

    Just an idea for you to try!

  7. Christian J. Carlo says:

    I have a pair of Saucony Virratas and they fit me great but I have a little bit of slippage on the heel. I think that a new thick insole would work for me but I don’t want to have an excess of cushioning, as the cushion on the Virratas are enough for me. Would a 7mm Merrell Insole work for me, or a thinner one?

  8. Do you have a recommended insole for extra cushioning? I love the fit of my Altra Instinct 1.5′s, but I develop a little bit of knee pain when I wear them for longer runs (14+ miles). I’m thinking a softer insole might be worth experimenting with before I relegate them to a different role.

    • The ortholites in this post are pretty soft. Only problem is I’m not sure how they’d fit in a shoe like the Altras since the toebox is unusually shaped.

      • Thanks. And yeah, the shape of the toebox is a bit of a concern of mine. It’s what makes the shoe great for me, but it makes something like this a bit challenging. I could always try buying a larger size insole and cutting it to shape/size.

  9. Hi Pete,
    Did you ever try out the Inov-8 3mm insoles in the Newton Energy? I’m curious as to how they fit. (Did they need to be trimmed, did they address the heal lift, etc.)

    Thanks,
    - Bill

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