Asics Metaspeed Sky vs Nike Alphafly – New Heir?


In today’s article, we’re going to be comparing the Asics Metaspeed Sky vs Nike Alphafly.

Nobody can deny that Nike Alphafly is the king of marathon shoes. But from Asics, a new challenger emerges.

But is the Asics Metaspeed Sky a legitimate heir or is it just a pretender to the throne?

Let’s dive right into it…


Asics Metaspeed Sky vs Nike Alphafly

I did 3x 2-mile reps at marathon to half marathon effort with 3 minutes of recovery in between each of those repetitions. This is the perfect workout for me to refresh my mind on what it feels like to run in these carbon fiber shoes and be able to put them head-to-head.

Again, the Metaspeed Sky and the Nike Alphafly are obviously two of the best complete super shoes on the market right now in my opinion.

They’ve got a full carbon plate running through their midsoles and they’ve got super foams sandwiching that plate to provide spring and bounce.

But first, let’s go over some of the specs…

Quick Specs

Nike Alphafly


The Nike Alphafly goes right up to that 40-millimeter limit set by World Athletics. So, the shoe has 40 millimeters of that wonderful ZoomX foam in the heel and 36 in the forefoot giving us a 4mm heel-to-toe drop.

That gigantic ZoomX stack height is combined with a carbon fiber plate and those giant dual Zoom Air bags upfront.

The upper is made out of AtomKnit which is the next generation of Flyknit. I’ve long been a fan of Flyknit and I enjoyed the AtomKnit even more.

AtomKnit is kind of a tight quite stiff weave and it does hold the foot quite well. It can be a little bit harder to get into the shoe with this bootie design as opposed to having a tongue like on the Metaspeed Sky.

On the outsole, there’s actually an ample amount of rubber coverage in the forefoot. Some would argue even too much rubber in the forefoot and there are some rubber skids along the sides of the heel to protect that precious ZoomX foam. 

This entire package comes in at a weight of 7.4 ounces, which is super lightweight for a shoe that looks a lot heavier than it actually is.


Asics Metaspeed Sky


For the Asics MetaSpeed Sky, we’ve got a little bit less stack height. We’ve got 38 millimeters of FF Turbo midsole foam stack height in the heel and 33 millimeters in the forefoot. There’s a little bit more of a drop with that 5-millimeter drop.

In this shoe, you also have a carbon fiber plate. The upper is a single-layer mesh that is super-strong even though it is very thin, very lightweight, and super breathable.

On the outsole, there is Asics Grip which is different from the AHAR which we’ve seen in a lot of other Asics shoes.

This is a lot lighter and there’s a lot less of it but it still provides plenty of that traction. Also, the Metaspeed Sky has some little heel skids, again, to protect that precious FF Turbo foam. 

This entire package feels like it’s a lot lighter, it looks like a much smaller shoe, but it’s only coming in at 0.1 of an ounce lighter at 7.3 ounces for US men’s size 9.

With those numbers and stats aside, what is it like to run in these shoes, and specifically, what is it like to run in these shoes as a non-elite but at marathon paces?

I think that’s where this comparison gets the most interesting.

ZoomX Midsole & Carbon Plate

First, let’s talk about the Alphafly…

Nike Alphafly


The Alphafly is very rightfully an extremely well-regarded shoe and a favorite among so many runners from the pro to the amateur runner alike.

It has a huge amount of that magnificent ZoomX foam which we’ve been seeing for a lot of years. Nike has been tinkering with Zoom X slightly, but I think they’ve really nailed down the composition making it very light, very soft, and very springy.

It has just that right amount of firmness and squishiness, but just a very quick response. ZoomX compresses and comes back very quickly with a high level of efficiency on my foot.

There’s just so much of it in the heel, which is going to give your foot a lot of protection from the impact and the repeat impact from all those foot strikes over the course of a marathon. 

In the forefoot, you’ve got an even softer material in that ZoomX foam. Softer is probably not the exact best word to use for it because when you’re just walking around, you’re not really compressing that airbag and so it might seem kind of firm and it almost seems like there’s almost a negative heel drop when you’re just walking around doing some warm-up paces.

But once you start getting up to speed like up to marathon pace, then you’re really starting to compress that airbag and push into it. So, as your foot hits the ground, it hits it and it just absorbs that impact really nicely.

These filaments (airbags) add a bit of a firmer feel to the forefoot part of the shoe and add a little bit more pop to your toe-off. They are designed to compress, and then as they release, they turn that kind of stored potential energy into kinetic energy, which pushes and gives back a lot of what you put into it with each foot strike.

Combine that with the carbon fiber plate that sits sandwiched right between a thin layer of that ZoomX foam and that Zoom Air pocket and you have a really nice system that just pushes your foot forward after it hits.

Asics Metaspeed Sky


FF Turbo is a brand-new foam that we haven’t seen before from Asics. It’s actually a souped-up version of the foam found in the Novablast training shoes.

It’s a nylon-based foam and it has a fairly similar feel to the Peba-based ZoomX foam you’re getting in the Alphafly.

The FF Turbo foam definitely reminds me a lot of ZoomX foam because it has a lot of those same magical qualities. I will have to say that of all the different super shoes that I’ve ever run in, that FF Turbo is probably the closest to ZoomX that I’ve ever experienced.

In the Metaspeed, you also have a carbon fiber plate, but I don’t get as strong of a carbon plate feel as in the Alphafly. I feel that the FF Turbo foam is doing a lot of the work and the foam is definitely the star.

It might not have been cast as the leading role, but it’s definitely in the leading role in the way that this shoe feels to me.

So, I did the exact same route and the exact same workout in the Metaspeed Sky and I got a very similar feeling as well in terms of that strength at marathon effort.

I just felt like I was in cruised control and I could have just done that forever. I felt like I was jogging, and every time I looked down at my watch to check on the pace, I just was surprised that I was going at the speed that I was given that I just felt like I was able to dial into a level of effort and just go.

Overall, the Metaspeed Sky really still works for me very well. I felt like I had plenty of strength at that marathon effort for the first and through the second rep.

By the end of the last rep, I was pushing closer towards threshold pace and maybe even a little faster than that because the workout kind of felt easy running in the Metaspeed Sky.

Upper & Fit

Nike Alphafly

nike-air-zoom-alphafly-next -upper

When it comes to the fit, both shoes have got quite lightweight uppers and fit true to size. However, the toe box on the Alphafly is not the most comfortable because you’re definitely getting a racer fit.

The Nike AtomKnit is basically a breathable see-through material that somehow still is very strong and is able to keep your foot well in place during the run.

But as much as I like this AtomKnit upper, the Alphafly narrows very considerably around the midfoot and some people with wider feet can find that they spill over a little bit and might feel a little bit unstable.

So, a lot of times, my toes end up getting crunched especially when I go on even longer runs. Again, during those longer runs, that snugness does start to add up and that’s really the main discomfort that I only ever feel in the Alphafly.

But I’ve never had any problems with rubbing or a lack of lockdown around the heel or the midfoot.


Difficulty finding running shoes for wide feet and narrow heels? Explore our related article for solutions.

Asics Metaspeed Sky


The Metaspeed Sky is more of a mesh. It’s got actually quite a similar amount of cushioning around the heel even if the tongue itself is fairly sparse on that front.

A lot of the things that I don’t love about the Alphafly also apply to the Metaspeed Sky as well.

The toe box is not the most comfortable and I’ll say it’s probably less comfortable than the Alphafly toe box because I just think that the lateral angle in the toe box cuts off really abruptly.

It doesn’t really give my foot enough space, especially towards those pinky toes towards the outside. But otherwise, the fit through the midfoot is really secure.

This single-layer mesh is very breathable, very lightweight, very strong, and so I don’t feel like it has any problem keeping my foot connected to the power that’s in this midsole and the carbon fiber plate.

Heel Cup

Asics and Nike go a little bit of a different approach in terms of the heel cup…

Nike Alphafly


In the back, the Alphafly has got those bumper pads that are sitting right on top of the heel and in between the heel and the ankle to keep people more secure in the back.


I feel like that’s plenty for me to stay stable in this shoe. Otherwise, there’s not a lot of structure in the back. There’s just a little bit right towards the base of the heel, but for the most part, it’s pretty flexible.

There is a little bit of a rise and this could dig into some people in their Achilles. But for me, I find that it hasn’t been a problem and the knit material is nice and soft.

Asics Metaspeed Sky


In the Metaspeed Sky, this heel cup is even floppier than what’s in the Alphafly and there is a little bit of padding but it’s more kind of like along this heel collar in the more traditional spot. They’re not doing a bumper system like the Alphafly, but I do prefer the fit of the Metaspeed Sky quite a bit.

A lot of the same stuff that went on in the Asics Metaracer upper, which I think is probably one of the best uppers that I’ve raced in recently, is translating back over into the upper for the Metaspeed Sky and that is a fantastic thing.

Once you put your foot in the Metaspeed Sky, it is not coming out. It is getting locked in there almost to a fault it takes a long time to get out of the shoe because the locking is just so good.

Stability & Tight Turns

One of the things that I was able to test on both shoes was what a sharp turn would feel like.


Nike Alphafly

I did a pretty tight turn in the Alphafly, and the high stack on this 40 millimeters plus the very squishy foam underfoot did lead to a little bit of ankle instability.

What it really translated to was not a feeling that my ankles were turning in or that it hurt, it just felt like I had to pull back from this perspective of “I don’t want to fall over.”

So, it does make you have to be a little bit more careful when the turns are tight and you’re running in the Alphafly.

So, if it was a 5k road race where I knew I would have more than one hairpin turn, then the Alphafly is a shoe that I’m not sure that I would reach for just because that stack height is so high.

Asics Metaspeed Sky

The Metaspeed Sky is slightly lower to the ground, but it feels like it’s so much more planted. I feel just much more stable on the ground in this shoe.

The FF Turbo might be a touch firmer than ZoomX and so I think that also helps in some of the stability when your foot is hitting the ground.

The width of the Metaspeed is narrower than the width of the Alphafly. But because this foam is a little bit firmer and because it is a little bit lower to the ground, I do feel much more confident taking turns in the Metaspeed Sky than in the Alphafly.

So, if it is a course that does have a lot of turns or has some hairpins, then I definitely would feel much more confident going into it with the Metaspeed Sky.

Looking for some great running shoes for narrow feet? Check out that article as well. 

Outsole & Grip


The Alphafly has got Nike’s traditional two strips of rubber and then quite a large amount of rubber on the forefoot, which should increase the grip and durability.


Like the Alphafly, the Metaspeed Sky has a similar design in the back, but the rubber doesn’t extend quite as far. The Metaspeed Sky has got a really quite generous covering on the forefoot and the shoe grips very well in all conditions.

On the day that I was testing the Metaspeed at these marathon paces, I had some wet conditions. But other than the fact that I was wet out there, I felt very sure-footed just as if it were completely dry conditions.

So, I’m a big fan of this Asics Grip rubber compound and I really like what they’re doing. I especially love the restraint that Asics put into the rubber outsole because they are not really known for having restraint when it comes to a rubber outsole.

Overall, I’m actually really proud of them for this one. They really nailed this fantastic outsole.

Which is more accessible?

I feel like anybody can run in the Alphafly. The Alphafly is a shoe that is very accessible to a lot of people of a lot of skill levels and a lot of paces. I feel like it’s very forgiving as well.

So, if you’ve got a sloppy footstrike or if you’ve got some other kind of inefficiencies in your stride, I think the Alphafly will overlook it.

On the other hand, I feel like the Metaspeed Sky takes a little bit more precision to drive in this one if that makes any sense. Once you’re starting to push things to limits, then having a little bit more skill might be required for this shoe because I just feel like it’s a little bit more finicky.

Even though it is a little bit more stable into the ground, I found that when my footstrikes started to get a little bit sloppy, I just felt like the shoe wasn’t as springy and poppy and I wasn’t getting the magic out of this shoe.

I felt like I was moving, but it didn’t feel quite as special. When my footstrike was a little bit more clean and when I was focusing on my form, then I really felt I hit that sweet spot.

I’m not saying that you’ve got to be some high-level elite to be able to run in the Metaspeed Sky. I just do think that it takes a little bit more thoughtfulness every once in a while to make sure you’re on the right path and getting the most out of the shoe.


Nike Alphafly

The Alphafly is a shoe that has become my go-to option for racing half marathon and marathon distance over the past 18 months. I set my half marathon PR in this twice although I did recently beat it while wearing the Vaporfly.


The Nike looks hefty and cumbersome, but once you start running at pace, it feels very natural, fast, and actually quite lightweight on the foot.

I’ve done a 5k race in the Alphafly and some track work and short reps and I feel it’s very fast despite the size. It really does help protect the legs and keep you firing throughout long races in particular.

When you lock into a good pace in the Alphafly, it can help you just maintain that for long stretches, which is why I really rate it for half marathon and marathon distance.

I don’t think it’s a shoe that you want to go kicking in at the end of a really hard-fought 5k and you want to sprint that last 500 meters. I don’t think it’s a specialty of this shoe. You can still run a fast 5k in it, but I think it’s a great option when you tend to get in that pace early and just try and hold it.

The Alphafly is a shoe where you want to run race pace all day, but it’s maybe not a shoe when you’re trying to edge out another runner.

In that respect, I think the Alphafly does differ from the Metaspeed Sky…

Asics Metaspeed Sky

I think the Metaspeed Sky is slightly nimbler and more versatile on those short races. It is a bit more lightweight and just smaller and you can turn on the gas at the end if you are feeling good.

The Metaspeed Sky is really comfortable, protects the legs really well, and is lightning fast.

I do think that even though it is a high stack shoe, it does feel slightly more nimble on foot than some of the other shoes that do go right up to that 40-millimeter limit.

It grips well around corners and I really don’t have anything bad to say about it.

I will say that as a heel striker, I have noticed that I’ve ripped up a bit of the exposed foam in the back. It’s nothing that’s affecting performance at all, but it might be something to keep an eye on if you’re a heel striker.

Overall, I certainly felt that the Metaspeed Sky was helping my performance in a similar way to other super shoes in terms of increasing efficiency and giving you that extra propulsion from the plate and also protecting your legs so you can finish strong in races. 

Asics Metaspeed Sky vs Nike Alphafly – Winner?

I think both the Asics Metaspeed Sky and the Nike Alphafly have a lot going for them. And if you are looking for a carbon racing shoe, then both are worth considering.

So, with all that being said, it’s been really tough for me to figure out which one of these two fantastic marathon shoes I prefer.

But I think for this battle, I’d say the Nike Alphafly is my top marathon pick and that’s certainly where I think it excels whereas I do think the Metaspeed Sky is a slightly more versatile shoe and it does have the edge of being a fair bit cheaper as well. 

When it comes to running the full 26.2, I feel like there is a sense of effortlessness to the Alphafly that I just think that the Metaspeed Sky, as fantastic of a shoe as it is, still just can’t beat.

I think the king is still the Alphafly when it comes to marathon pace racing.

I would go for the Alphafly when it comes to longer distances, but the Metaspeed Sky is still going to do a good job at those distances while being less of a monster than the Alphafly.

But maybe if you’re looking for one carbon racing shoe to do all your training and racing as well, the Metaspeed Sky might just have the edge. I think it is a better 5k shoe or 10k shoe.

The Alphafly is still going to be fine over 5ks and 10ks and you’re not going to run very slowly in those races because it’s a big shoe.

But when it comes to the marathon, it really does shine. You can settle into that pace, just tick along, and hit your race goals. It will protect you, provide some propulsion, and just feel fantastic underfoot. Once you’re running it, you really don’t start to think about how big it is unless you look down.

Overall, both are great shoes. The Metaspeed Sky is slightly more versatile and a bit cheaper, but, again, the Nike Alphafly is still the king of the marathon for me.

Where to buy Metaspeed Sky (not affiliate)
AsicsRoadrunner Sports
Where to buy Alphafly (not affiliate)
NikeRunning Warehouse

Let me know in the comments if you have any questions about either of these two shoes or if you disagree with my opinions.

I’d love to hear about it. 

That’s all I have for today, everybody.

Thanks so much for making it to the end of this Asics Metaspeed Sky vs. Nike Alphafly comparison. Hopefully, you guys are staying safe out there on your runs and I’ll see you in the next one.

About Eric Barber

Eric Barber is a happy father of two little angels, a husband, and a runner. He eats, sleeps, and dreams anything foot related: running shoes, walking shoes, sneakers, you name it. It all started when Eric was a shoe store specialist watching and fitting people's feet day in and day out.

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