Alphaflys a bust?

Milethon wrote:

I haven't tried the Alphaflys but from the reviews and descriptions, I'm going to stick with the Next% . They are about as perfect as a shoe can get for me, unless Nike can figure out a way of shaving off an other ounce or two. Also a trail version of it would be pretty cool.

Do you think we might see a 1-2 oz reduction prior to Tokyo?

Only counter argument to all this is that Kipchoge ran 1:59 in them and Rupp killed Atlanta in them as well.

What use is it to know your easy pace got faster for what is supposed to be a race day shoe ?

pcli5kdoc wrote:

Milethon wrote:

I haven't tried the Alphaflys but from the reviews and descriptions, I'm going to stick with the Next% . They are about as perfect as a shoe can get for me, unless Nike can figure out a way of shaving off an other ounce or two. Also a trail version of it would be pretty cool.

Do you think we might see a 1-2 oz reduction prior to Tokyo?

I would say objectively no chance and here is why

1) The uppers on the lightest of their elite product (the nxt%) are already are as minimal as possible and to be honest pretty terrible. They had to use a non-breathable ripstop on the nxt% in order to have an upper that had no internal reinforcement etc because it would add weight (ie. a mesh with any sort of physical openings in it for breathability/airflow would simply stretch too much and need added support). They nicely framed it up as "water resistant to stop water soaking into the shoe and adding weight" but really it's a crappy but very lightweight upper.

2) Outsole rubber is the densest material used on footwear so they try and keep that to a minimum. Hard to see where you use less rubber than on the current nxt.

3) Midsole unit (foam and plate). Here is the thing - the key biomechanical advantage is created by the curvature of the plate and ability of the foam to compress into the void, creating a 12-14mm "drop". So when you think about it that way, the midsole needs a certain geometry in order to do these things a) have some foam between the plate and the outsole rubber - around 10mm b) house the plate (around 2mm) and c) have that 12-14mm for the "drop". So that means forefoot wise around 26mm for the actual foam unit. When you add in the rubber and the sockliner and then adjust the rearfoot to create the basic forefoot to rearfoot drop, you end up right at the current limits of World Athletics rules.

So what's my point? The way to reduce weight on this shoe is to reduce the midsole unit but doing so takes away from the running economy improvement levers/factors the shoe has. In that respect the only way you make this shoe lighter and keep those factors is to use a lighter rubber and/or foam and considering the foam is some ridiculously low density already (in the 010-012C range), there isn't much to play with that could ever see you dropping 1-2 ounces.

If Nike could squeeze this down even 14 grams (which is 1/2 an ounce) and keep it as economical it would be amazing.

Hardloper wrote:

I've done lots of workouts in the Alphaflys and ultimately decided to stick with the Next% for my recent marathon. I doubt you have scientifically measured your "energy return" in each shoe.

What kind of workouts did you use to test the shoes?

For shorter faster stuff I do prefer the Vaporfly (would even use them for a 5k), but for me where the Alphafly's show their real strength is long sustained pace efforts. Long tempo runs are a dream in them. It feels like you can hit a hard pace and just hold it forever. Vaporfly's are great and I love them, but there is something specifically about the airpods in the Alphafly which work really well for me and my mechanics./foot strike. What's interesting is that I also normally prefer a narrow shoe (do most of my intervals in adidas adios), but I think maybe because of the stack height, I actually prefer the more stable base on the Alphafly. I like going into a corner better in them than the vaporfly.

The worst part of these shoes is the price and availability, because for me the key takeaway is that people really need to try them both and see how they feel, and that's hard to do when it's very difficult to get a pair and they are so expensive.

I loved the way Alphas felt on the run, but they totally left my arches trashed. I've seen a few similar complaints and for that reason alone I had to go back to my VF Next's. Maybe the decoupled forefoot and heel put too much load on my arches? Who knows.

Look that Mens

1 Vaporfly next%

2 Adizero Adiós Pro

3 Vaporfly next%

Womens

1 Adizero Adiós Pro

2 Adizero Adiós Pro

3 Vaporfly next%

Runner7 wrote:

Look that Mens

1 Vaporfly next%

2 Adizero Adiós Pro

3 Vaporfly next%

Womens

1 Adizero Adiós Pro

2 Adizero Adiós Pro

3 Vaporfly next%

Ok. And since the addidas weigh more than the alphafly, the observations about weight being important clearly have been all wrong. Right?

1 percent faster wrote:

No, the Alphafly’s are more durable. They used a thicker rubber on the forefoot and heel, and the cushioning stays springy. I go by heel wear, and I’m getting more wear out of the Alphafly’s than any previous version of Vaporfly’s.

Can you make up your mind please? How come you say they are more durable yet say you are getting more wear out of the Alphafly?

Hold on now.... wrote:

The only thing truly groundbreaking or even remarkable is that a thread about a Nike product was started by someone other than a Nike employee. I mean, they weigh in once they see it on the Board, but a civilian felt the need to start it.

A civilian? Hahahahahahaha!

Where you get the idea Nike is a branch of the military?

speed work as your test? wrote:

Ok. And since the addidas weigh more than the alphafly, the observations about weight being important clearly have been all wrong. Right?

Weight is important, as is energy return. But it's hard to detect tiny differences in efficiency without a proper lab test. Both shoes feel good for long runs and long MP efforts, and I have no way of knowing if I would have run slightly faster in the other shoe in the exact same conditions. So I stuck with the next% for races because 1) it was slightly more comfortable, 2) I prefer higher heel-to-toe drop and am a bit of a forefoot striker even in marathons 3) external data like the fact that many Nike athletes are still using the next% and posters like Salvitore Stichmo (who probably works in the shoe industry).

^^^one OC the best posters on this site, in my opinion. Very dialed in.

Hardloper wrote:

speed work as your test? wrote:

Ok. And since the addidas weigh more than the alphafly, the observations about weight being important clearly have been all wrong. Right?

Weight is important, as is energy return. But it's hard to detect tiny differences in efficiency without a proper lab test. Both shoes feel good for long runs and long MP efforts, and I have no way of knowing if I would have run slightly faster in the other shoe in the exact same conditions. So I stuck with the next% for races because 1) it was slightly more comfortable, 2) I prefer higher heel-to-toe drop and am a bit of a forefoot striker even in marathons 3) external data like the fact that many Nike athletes are still using the next% and posters like Salvitore Stichmo (who probably works in the shoe industry).

Weight is still the easiest quantitative metric when it comes to running economy/efficiency of a shoe. 100 grams is equivalent to 1%. The adios is 235g and the Vapes are 195g. So in lab conditions the nxt% has a 0.40% advantage already.

The remaining factors/drivers of economy are

1) the resiliency (rebound effect/"energy return") of the foam

2) the curvature of the plate (and how much the foam allows you to "drop" forwards into that curvature when you strike) which creates the forwards promotion of your center of mass and changes the force vector of your foot strike

3) The ability of the midsole in general to compress as quickly as possible and allow maximum force transfer to the surface you are running on

4) reduction in work of your MTP and ankle joints due to the rigidity of the midsole (created by the plate - same logic as used in spikes for the last um, 50 years)

That's your golden 5 factors of running economy with respect to footwear.

Good stuff! So, as between the Alphafly and the Adios Pro, where the Adios is a heavier shoe, do you think the "lightstrike pro" foam in the forefoot provides so much more resiliency than the Alphafly "zoom pods" that they end up being a better shoe even though they are heavier? IN general, does that mean the "lightstrike pro" is a better foam than ZoomX foam?

(Note: you have never said the adios is a better shoe, just going by others)

Nobody here claimed the Adios is a better shoe than the Alphafly.

Hardloper wrote:

Nobody here claimed the Adios is a better shoe than the Alphafly.

In your original post you made the claim that alphafly's weren't a better shoe as proven by the fact that Kipchoge ran a race and lost in them. Other's on this thread (and elsewhere) look at the shoe an athlete is wearing who wins a race as evidence that it's a superior shoe (like the first response), but then specifically Runner7 listed the shoes worn by the top three male and female athletes. So, yeah, people on this thread did correlate the shoe an athlete was wearing with how good it was and the top two women were wearing Adios Pro and third place was Vaporfly.

All that being said - I clearly just said "going by others" without specifying who those others were other than it wasn't SS.

In conclusion, other than being slow as fvck as a runner, mentally you are as well. Thanks for your response, Ed.

I’m running a mile time trial tomorrow on the track and shooting for something un 5. I have a fresh pair of the VF Next with the waffle outsole and a pair of Alphafly with 13 miles on them.

I’m loving the Tempo Next for training runs and am used to running on the air pods so I know the AF are good with my foot strike and stride.

I haven’t touched a track in a while so I’m unsure if the AF aren’t great on the turns. Any recommendation if I should go with the VF Next of AF.

Thanks

Alphafly’s are fine on gradual turns, such as a track. No better or worse than the vaporfly in my opinion.

Here is what we would need to do to test that. We would take the zoom pod and measure it against a identically sized chunk of l/s pro using a set impulse against a force plate. Impulse is more important than just pure force because impulse is a measure of force in a certain time frame (hence the SI measure is Newton per second) and clearly in the running gait cycle we apply a force which only happens over a certain period of time depending on how good we are, (faster runners not only apply more force but in a shorter period of time which is why their impulse values are off the charts compared to the average runner). The greater the force we see registered on the plate the more we would assume is returned to the runner (based on Newtons third law of the conservation of energy).

Do I personally know what the result would be between l/s pro and a zoom pod? No. But for me personally I would almost always prefer a foam with homogenous cell structure to a complex manufactured part like the zoom pod which has the TPU casing and the molded interior structure I would guess is also some kind of injected elastomer. No doubt a pod of foam is fundamentally lighter than an assembled pod which is it's first example. I have held zoom pod parts (you can too if you want to rip apart a shoe) and even just based on hand feel it's not like I think it has some otherworldly resiliency or rebound - it compresses and rebounds in a standard elastic fashion.

What you really need to take into account is that there are so many factors involved because, in particular, the zoom pod is part of a system of foam+plate+pod+rubber and you have to understand that things like the adhesive layers that stick it all together impact it's properties. Another reason I like simple foams that are lightweight and have high tensional resilience.

Which leads us to l/s pro vs Zoom X foam. Well look, there is a reason the Vaporfly is 40g lighter. I am sure some of it is upper related (but not much) - remember my original post pointed out the heaviest element of any athletic shoe by far is the midsole and the primary constituent is the foam. If we assume that the outsole rubbers and plated systems are similar in weight, then zoom X must be the lighter foam. With respect to the key metric of tensional resilience? Draw your own conclusions on that one. Here is a way you could think of it - think of a rubber band stretched 1.5 times its original length and the same rubber band then stretched 2 times it's original length. The way those rubber band feel when you depress them say an inch is the way differences in tensional resilience feel. Higher resilience is better in this respect for performance running product. That's all I'll say.