ALPHAFLY AT TRIALS - letsrun please get a definitive statement from USATF

The Adizero rush had a nylon flat plate, the advantage of f the toe spring was lost due to increased work at the ankle. The Nike plate is spoon shaped, like a leaf spring, they've also patented the shape so nobody can create something similar. Something that Adidas, Fila etc... Didn't do with the small flat nylon and carbon plates of the 90s. I just don't get this argument, who do you want to win? The better athlete or the better tech?

I've seen this argument all over the place. Lets say someone makes a shoe which returns exactly the same energy as you put in (which would pass your criteria). All the runner would have to do is run one really fast step and then bounce at the same speed all the way to the finish.

Malemute wrote:

At least Lagat has the Alphafly. I imagine most of the Nike athletes will have them if they aren't banned before the Trials. A little worrying.

https://twitter.com/ChrisChavez/status/1221900554001100802

ANY athlete that wishes to wear them in Atlanta will be given the opportunity.

HotLanta wrote:

Malemute wrote:

At least Lagat has the Alphafly. I imagine most of the Nike athletes will have them if they aren't banned before the Trials. A little worrying.

https://twitter.com/ChrisChavez/status/1221900554001100802

ANY athlete that wishes to wear them in Atlanta will be given the opportunity.

You keep saying this. I don't believe you. I find it hard to believe everyone will be handed a pair. Offer up some proof.

The problem with this claim is that the scientists have said that there is an added advantage in adaption to the shoe. Using the shoe your body responds differently and muscles and tendons are affected differently. So those preparing in them are already ahead of the game. The idea of people turning up and being given a pair of shoes to race Innis ludicrous. Just take them away from the people who have them. If Federer turned up with a racket 24 inches across we'd all cry foul. These things don't even look like shoes anymore. It's a joke, I'd be embarrassed to line up in those things.

bugattiaron wrote:

Bromka was wearing the Next% with a custom, unbranded upper. The midsole was the exact same as the Vaporfly Next%, and the upper appeared to be made of Vaporweave. It was his custom pair.

No, Nike.com let you customize the upper and sole on the Green Next% when they came out last summer. You could pick any upper of the 3 Vaporfly’s and either the current or the small waffled sole that was on the Streak LTs a few yrs ago. I wish they kept allowing for this when the pink ones came out.

Xfinity wrote:

HotLanta wrote:

ANY athlete that wishes to wear them in Atlanta will be given the opportunity.

You keep saying this. I don't believe you. I find it hard to believe everyone will be handed a pair. Offer up some proof.

Everyone will get the option to have a pair to race in. It's the athlete's personal choice if they want to accept a pair and race in them or not. Believe me or not, I don't give a śhit.

butttt wrote:

I've seen this argument all over the place. Lets say someone makes a shoe which returns exactly the same energy as you put in (which would pass your criteria). All the runner would have to do is run one really fast step and then bounce at the same speed all the way to the finish.

That’s not how 100% energy return would work. You’re describing a perpetual motion machine.

If you put X joules of energy into a stride and the shoe returns that same energy back but it is still dissipated and more force needs to be put back into the next stride.

Raggedman wrote:

butttt wrote:

I've seen this argument all over the place. Lets say someone makes a shoe which returns exactly the same energy as you put in (which would pass your criteria). All the runner would have to do is run one really fast step and then bounce at the same speed all the way to the finish.

That’s not how 100% energy return would work. You’re describing a perpetual motion machine.

If you put X joules of energy into a stride and the shoe returns that same energy back but it is still dissipated and more force needs to be put back into the next stride.

I think he is correct actually. In reality no material will have 100% energy return, but physically if such a material existed you could just bounce along.

Dubyah wrote:

KraftMacAndCheese wrote:

In my wildest dreams I would be given them.

Bromka wore the next% at CIM

Why bring this up? Them as in the Alphafly's. From the thread title. Is this mor clear? Kudos to him for not wearing the Alphafly in 2019 at CIM or at Houston 2020. The Next% is available everywhere. The Alphafly is still a prototype.

Xfinity wrote:

You keep saying this. I don't believe you. I find it hard to believe everyone will be handed a pair. Offer up some proof.

Agree. How'd they know how many of each size to stock at the check-in table? 700+ runners in the trials.

HotLanta wrote:

dodge ball wrote:

Even to someone sponsored by Adidas?

Yes, available to all.

They should level the playing field and just make everyone run in Crocs.

Sit and kick wrote:

Raggedman wrote:

That’s not how 100% energy return would work. You’re describing a perpetual motion machine.

If you put X joules of energy into a stride and the shoe returns that same energy back but it is still dissipated and more force needs to be put back into the next stride.

I think he is correct actually. In reality no material will have 100% energy return, but physically if such a material existed you could just bounce along.

And friction would lose you no energy at all? Good luck with running in a vacuum then...

100% return is impossible, but even if it was approached at 95% you're only talking about the energy put into the shoe. Everything else, from overcoming friction, work / heat in the body, etc etc costs energy. The shoes as it is are about 85% return, so there's not much more that will be extracted.

larkimm wrote:

Sit and kick wrote:

I think he is correct actually. In reality no material will have 100% energy return, but physically if such a material existed you could just bounce along.

And friction would lose you no energy at all? Good luck with running in a vacuum then...

100% return is impossible, but even if it was approached at 95% you're only talking about the energy put into the shoe. Everything else, from overcoming friction, work / heat in the body, etc etc costs energy. The shoes as it is are about 85% return, so there's not much more that will be extracted.

There's a massive difference between 95% energy return and 85%. 95% energy return means you can maintain 3 times the kinetic energy (or 73% faster speed) than at 85%. Think of a bike or inline skates as something approaching 100% energy return. You still provide all the power but you can maintain a much higher velocity because you're not losing energy every footstrike.

Hardloper wrote:

larkimm wrote:

And friction would lose you no energy at all? Good luck with running in a vacuum then...

100% return is impossible, but even if it was approached at 95% you're only talking about the energy put into the shoe. Everything else, from overcoming friction, work / heat in the body, etc etc costs energy. The shoes as it is are about 85% return, so there's not much more that will be extracted.

There's a massive difference between 95% energy return and 85%. 95% energy return means you can maintain 3 times the kinetic energy (or 73% faster speed) than at 85%. Think of a bike or inline skates as something approaching 100% energy return. You still provide all the power but you can maintain a much higher velocity because you're not losing energy every footstrike.

I'm an engineer an trying my best to understand how you came up with these figures but seriously struggling. Are you suggesting that if shoes returned 10% more of the energy put into them the world record would be in the vicinity of 1h15m-1h20m?

and am*

DietBacon wrote:

Hardloper wrote:

There's a massive difference between 95% energy return and 85%. 95% energy return means you can maintain 3 times the kinetic energy (or 73% faster speed) than at 85%. Think of a bike or inline skates as something approaching 100% energy return. You still provide all the power but you can maintain a much higher velocity because you're not losing energy every footstrike.

I'm an engineer an trying my best to understand how you came up with these figures but seriously struggling. Are you suggesting that if shoes returned 10% more of the energy put into them the world record would be in the vicinity of 1h15m-1h20m?

Oh I think I understand now. You're saying that if we only lost 5% of our energy through our shoes we'd maintain 3x the kinetic energy than if we lost 15% because 3x5%=15%.

The issue with that thinking is that we don't only lose energy through our shoes. Our bodies produce heat, there's wind drag, heat/sound produced due to friction/collision of your body with clothes, shoes, ground, etc.

In reality the energy return from the shoes is only from your vertical displacement, and not even all of it, because some is dissipated through other means before your footstrike.

A shoe with wheels doesn't return more energy than is put in to it

WTF ...

https://www.instagram.com/p/B7z3q3cnToI/?igshid=13rlhqfzqf0ne