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Altra 3-SUM Zero Drop Running Shoe Review

Altra 3-sum Triathlon

This is a guest review by John Shepard (@runsheprun on Twitter). John is the owner of Take it on the Run, a boutique running store that he runs out of his home. John is an Altra vendor, and over the past few months has been trying out the recently released 3-SUM Tri shoe. I asked if he’d be willing to write a guest review since I’m not a triathlete, and he gladly agreed. Here’s what he has to say:

Altra 3-SUM Review

I started dabbling in Triathlons last summer. Why? I have no clue, but I got my hands on a free bike (think “American Flyers” starring Kevin Costner era bike) and I had a neighborhood pool to swim in. So, I went with it…

After I was finished with my first Tri, I was immediately thinking of ways to get faster… just like I do after every other race that I’ve ever finished. One area for improvement in the race was in the 2nd transition area where I literally sat there and laced up my shoes (coincidently Altra Instinct 1.5s). It felt like it took me 3 hours to tie the shoes. I needed to change what was on my feet if I was going to banish the “What if…” voices from my head.

Enter the Altra 3-SUM. Even if I wasn’t in the business of selling shoes, I’m a shoe geek, and I get pretty excited about new shoe releases. I was beyond my normal level of excitement however when Altra came out with the 3-SUM. It was going to fill some voids in my shoe arsenal. 1) I needed a racing flat. Racing flats are tough for me to fit in because of my size 14, extra wide foot. 2) I am planning on doing more and more Tri’s. 3) They are a big departure from the aesthetics of Altra’s original shoes. Color Poppin’!

Altra 3-sum side

Ok, so let’s get down to the nitty gritty of the shoe itself. I have put some good miles on them in the last 2 months and here’s my opinion. They are a great racing flat. Altra does one thing better than any brand of shoe that I have tried on: consistency. They keep the fit of their shoes the same. I can go across the brand and know that my foot will fit exactly the same in each make. I know many people have had issues with their sizing (trust me, I sell them and have had a lot of returns), but once your Altra sizing dialed in, expect the same fit across the brand.

Altra 3-sum top

Characteristic Altra Foot-Shaped Last

One differentiator from the rest of the Altra line is that the 3-SUM is lower profile (18mm) than, say, the Instinct 1.5 or Provision. This gives them great ground feel. As someone who isn’t used to low profile shoes on pavement, my feet were barking at me after competing in the River to River Relay where I ran three 5k’s in them in one day. You will feel the pavement for sure. However, this is characteristic of just about any racing flat.

Another characteristic of a racing flat is that they tend to be lightweight. Altra delivered here, with the 3-SUM topping the scales at only 6.7 oz! When I first slipped these on, I was immediately impressed by how light they were. Funny how just a couple of ounces less on your feet can make you feel faster. Not sure if it was a mental thing or the shoes, but I PR’d my 5K time in the first leg of that relay race.

Altra 3-Sum sole

Altra 3-SUM Sole – note the full rubber outsole and the drain holes

Ok, so with every good comes some bad, and I have only a few concerns about the 3-SUM. First off let me make sure that I state this clearly… THESE ARE DESIGNED TO BE A TRI SHOE. Yes, I know it’s obvious, but if you want just a racing flat and don’t plan to compete in triathlons, buy The ONE from Altra.

Here’s why:

The lacing. Altra teamed up with Yankz to provide their drawstrings as laces on these shoes. I totally get it. You won’t be that moron sitting there tying your shoes in a race (i.e., me – see above). However, what I’ve noticed is that it takes a bit of practice with the lacing to figure out the right fit. And no matter how much you think you have tightened each shoe the same, you haven’t. Each foot requires its own combination of tightening and loosening. Furthermore, if you lace your shoes any special way, it’s near impossible to do so with the Yankz. I know this seems like more of a problem with Yankz, but they’re the laces you get with the shoe.

The other big problem – blisters! Tri shoes are typically meant to be worn sockless. It’s a time game, and putting on socks adds time to the transition. This is why most of the elites don’t wear socks. I took the 3-SUMs out sockless for the first time for just a mile and got a blister on the top of my foot. This could have been due to the issue above with the Yankz, but I can’t be certain. Either way, blisters are no bueno. I did remedy this by putting on socks. By no stretch of the imagination do I see myself winning any races in my career, so I don’t care about putting socks on in transition. But, if you aim to shave every nanosecond from your transition, this is a consideration.

Finally, the name. I am just kind of shocked that a name like that could get through. Maybe my head is eternally in the gutter or something. “Having shoe issues? Try a 3-SUM.” Anyway, I just think there are other names to use that reference 3 than that.

So, if you are in the market for a great zero drop Tri shoe, and you don’t mind wearing socks, the 3-SUM is the way to go.

To learn more about John’s approach to selling shoes, or to buy a pair from him, visit Take it on the Run (disclosure: I do not have an affiliate relationship with John, just helping out a friend and fellow shoe junkie!).

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About Peter Larson

This post was authored by Peter Larson. Pete is a biology teacher, track/soccer coach, and dad (x3) with a passion for running, soccer, and science. If you'd like to learn a little bit more about who I am and what I do, click here, or visit


  1. Maybe this is a naive question, but what is the difference between this shoe and “The One”? I’m not a triathlete (too much swimming…). The specs look similar.

    • Pete Larson says:

      The One has a more traditional tongue and lacing system. Same sole I think.

      • John Shepard says:

        That’s correct Pete. They have a different upper material also. Altra really tried to get the “no socks thing” right and did a seamless upper and did some anti-odor/anti-bacteria treatments as well to the 3-SUM

  2. Brian Hazard says:

    I’m an Altra fanatic myself, but my sizing is not consistent among models. I’m a 9.5 (my “normal” shoe size) in The One and the Lone Peak 1.5, but a 10 in the Instinct, Instinct 1.5, and Torin. Even the Altra site says the original Instinct runs small. For what it’s worth…

    • Pete Larson says:

      I have similar issues, I think what he was trying to say is that the fit of the Altra last is consistent once you get the correct size, but I could be wrong on that.

      • Brian Hazard says:

        The phrase “once your Altra sizing dialed in, expect the same fit across the brand” is what prompted me to comment. As for the actual fit, I find that The One (and therefore the 3-SUM) provide a little extra room for the big toe to splay. I’ve got a blister on the inside of my right big toe that gets aggravated in every other shoe but The One.

        • John Shepard says:

          Brian, you are correct. I have had the same size of Altras across every shoe they’ve come out with. Sadly I have every single one. It might be due to me being a larger size where there’s no half size for me to play around with. Its either a 13 is too small and 14 is just right.

  3. Any insider info: Altra in Europe?

  4. Scott Revlin says:

    Really wanted to like these, but I could not get my heel to stop slipping around, even after downsizing a full size from my other Altras. I’m a frequent user of lace pulls so I don’t think this was a lacing issue (although an additional eyelet probably would have solved the problem).

  5. Doug Robertson says:

    I’m pretty excited about these, until I get to the blister part. Not sure how I feel about needing to wear socks.

  6. Chris Gordon says:

    I just bought the 3-SUM, and I’m excited to try them. However, that’s not why I’m commenting. I just want to say that this is the most civil comment thread I have seen in a long time. Thank you for that!

    Leave it to runners to show everyone else how to live.

  7. Just recently started running and not realizing this was a tri shoe, I bought it for a great price I found and jumped on it..i do a lot of trail events(OCR) but started running on a local pavement course and my trail shoes don’t work well for that..will these workout for pavement running?(ordered but not received yet) thank you!

  8. I run in the 3sums for anything up to 10km or OD triathlons with no socks.
    They are fantastic.
    This weekend I did a half iron distance in them, with no socks. That was probably a little bit too far and my feet were a little sore by the end.

  9. Jynxy or Jill in Texas says:

    I have had a few altras now. I am not loving that they wear out around 250 miles, but I keep buying them because they are the most comfortable shoes for me. They literally changed my life. I have bunions. I didn’t even know what a bunion was until a few years ago when I started running and all running shoes hurt my feet. Anyways, I love altras.

    I got these shoes, and alas… I am not in love. I wear them for walking around and just doing stuff, because I like how they look and people asking me questions about them, but they rub so this pair is not doing it for me. I don’t know why, as only one of my feet rub in these shoes. The other foot is fine. That plastic that goes over the toes is really no bueno. I wish these were exactly like this, but take away that plastic smear that is over the top of the toes to the tongue area.

  10. I LOVE these shoes. I trained for and ran an ironman in them last summer (with socks) and felt awesome. The foot-shaped shoes allow for swelling during the race so I didn’t have extra pressure or pain. As for blisters, I run 1/2 marathons in these without socks. I don’t have a problem but I did dial in the laces (pretty loose) and I worked myself up to 1/2 marathon distance with/without socks to allow my feet time to adjust. They are worth a shot if you are interested in triathlon. I love that the tongue is incorporated into the shoe and they are so fast to put on and go during a race or for your morning run!

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