I'll let others respond in a "scientific" way.

What I notice while watching some of the marathons/Ironmans taking place this year: the Alphafly's seem to be used when the route is fairly straight-forward, while the Next% are used when the route its a bit more twist-&-turn course.

So sorry this is not 100% responsive, but you and I are approximately the same size. I am 5 years older and you are faster. I LOVE the Next % and believe they are quite superior to the Carbon X. I think it is the foam, not the plate that makes them so magical. The really surprising thing is that I have an old ankle injury for which I have had to have either orthotics or some other sort of good arch/heel support in all my shoes, so I didn't think I could wear these shoes but gave them a try. In the Next % I have no ankle issues whatsoever. Really rather amazing. I am going to try to Alphafly as soon as I find a place where I can try them on.

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David
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The stack height of the Alpha’s maybe makes them a bit less stable when cornering?

I'm older than you and own both shoes.
At "hopeful " IM pace (9:00/mile), the next% is a much better shoe for me. At about 8:00/mile the AF performs better but still prefer the N% at that pace.

It seems like the Next% are more popular for a lot of people and some people have issues with the Alphafly for one reason or another

All that being said if you are planning on using it for an IM consider what pace you are going to be running at. I forget the exact pace but some people have said they become uncomfortable/awkward if running slower than 7 min/mile but really not still not getting the full benefit until around 6 min/mile

Edit: Decided to add some additional useful advice that the saucony endorphin pros were often reported as being more comfortable at slower paces compared to the equivalent nike shoes while still being a great shoe for faster paces. My current plan is to use these for half and full distance races in the future

I use both and love both. The Next% feels tall and squishy.. until you try the Alphafly. And I think if you are injury prone or trying to be proactive, I personally would go with the Alphafly for the extra cushion it provides. That is my subjective opinion, and it feels weird saying that simply because the Next% was considered exceptionally tall and cushioned by most people's standards for a long time. The Alpha is one ounce heavier than the Next% (in size 11), but it's hard to tell when wearing it.

If price is not an issue, I personally would go with the Alphafly. I've purchased new Next% on eBay for under $200, which makes it pretty reasonable though.

Such a tough choice. And any talk about having to run a certain pace to get the full benefit.. I don't buy into that. Both feel great to me at any pace, whether I'm jogging the first mile of a long run or doing intervals and strides.

I've tested both at the same time, back to back, and preferred the Vaporfly. The Vapors feel great at all speeds, felt better walking, and felt better if I altered my foot strike a little. On really long runs, I'll move my foot strike around a little to help with muscle fatigue, plus I sometimes have discomfort from mild arthritis in my foot that is alleviated by altering my foot strike.

The Vapors also fit my feet a lot better, but that's to unique to a particular person.

The Alphas felt fantastic at an uptempo pace, and the perceived effort was *slightly* lower at that pace compared to the Vaporfly. However, at slower paces the Alphas felt awkward due to the front pod, and the pods also meant you really need strike very mid to forefoot. They're also make a noise with every step, I think from the footpod compressing. Not a big deal - just an observation.

Quick note on the names, because I see a lot of references to Alphafly vs "Next%. Both of these shoes have "Next%" at the end of their model names, i.e., Alphafly Next% and Vaporfly Next%.

I don’t think you will find anything definitive here. It comes down to fit and feel between the two or actually three shoes. In the end the Carbon X might be your shoe. If you look at the Nike runners only at the front of the marathon it’s about 85% Alpha Fly and 15% Next %. Kenesisa Bekele the greatest runner over multiple distances in history wears the Next % over the Alpha Fly.

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Dave Jewell
Free Run Speed

The shoes have a distinctive different feel to them. You definitely can feel the air bubbles in the alphas.


I think its actually not so much the pace you run but the form (which is often dictated by the pace).
In my experience, to get the full benefit of the alphas you need to land toes first, have a nice kick and high(er) cadence. Unless you really focus on it, its harder in lower pace.
The next% is more "forgiving" and you feel like you get the energy return/pop/whatever you want to call it, even without focusing hard on form (though when you do focus you get more)

After a few runs in the alphas I thought I'll never buy them again and go back to next%, but having spent more time in them they grew on me. As long as I do my part wrt form, I think I get more from the shoe
just my 2c, but as others said its very nuanced and slight differences. Both are fantastic shoes.

My advice, just get both in your size and test them out. You can free return to Nike/running warehouse/etc. if you don't abuse the shoe

Haven’t used the Alphafly, but the Next% are much more stable than the 4%. Wore the 4% in my last IM with a 3:22 run and the Next% in most recent HIM with a 1:27 run. Didn’t have the Next% for the IM, which was June of 2019. Really like the Next% and have worn them a bit for some fun runs this year w/out any races to do.

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Seth James DeMoor did a good comparison on his YouTube channel on this topic. Seems like a lot of professionals stick with the Next% due to a few factors, weight being one of them.

I think the Next% will be getting an update for 2021.

I rotate between both the Next and Alpha for all types of road running sessions. I've used every version of the Nike Carbon plated shoes and tried Saucony Pro Endorphin, New Balance's T Cell, and Adidas Carbon (though didn't run in these).

Nike just has a 3-4 year lead on all Carbon plated shoes. I think it's more than the plate, it's the foam. I was really hoping Saucony Pro would've worked better, but it's so stiff and "bottom" heavy. I've heard the Speed is much better overall with a more responsiveness. New Balance and Adidas (what I've heard) are just behind. Hopefully this all changes over the next few years, but Nike seems to have a big lead.

Initially I thought the Next was better given the weight and slightly tighter fit, but over time, the Alpha has blossomed. The foam just makes going fast so easy and your don't feel beat up at all. I'd say Next might be "faster" over a shorter course up to a half marathon. As with others, the Next seems to have a more secure feeling especially if you have more turns. If the course is relatively straight forward and over a marathon, I might choose an Alphafly.

The endorphin pro and speed are two different animals. The pro has more "pop" than the speed and the Vaporfly. The Vaporfly has more "bounce" The speed has neither of these. Its a trainer and its squishy with a soft nylon plate that is a tad springy but nothing like the pro or vaporfly. The speed is an outstanding trainer but for a race you're giving up some energy return......however the speed is not built to "pop". It's built to be a every day trainer that's light and soft. This is does very well.

The noticeable differences in the Pro and Vaporfly are:

1. Pro "rolls and pops" where the Vaprofly "bounces".

2. The Vaporfly is more squishy than the Pro.

3. The Pro is more stable and doesn't penalize you if you heal strike. The Vaporfly is less stable and demands more of a forefoot strike.

4. The Vaporfly is a tad lighter.

5. The Pro is much more durable.

Both are really good shoes and if one doesn't work for you most likely the other will. I have ruled out the AF because of the weight and price.