Dragonfly spikes Cheptegei was wearing: they aren't actually carbon fiber, correct?

Renato Canova wrote:

Now, we have the same WR holder for the distance of 5 km (road) and 5000m (track). Cheptegei ran his WR on the road wearing Vaporfly (12'51"), ed his WR on track wearing Dragonfly with spikes (12'35"). Similar conditions of shape, fast race on the road in Valencia, and better weather compared with Monaco. At the end, we have a difference of 3" per km, clearly showing Dragonfly are, on track, faster than Vaporlfy.

No one can say what Cheptegei 's full potential is and how much his fitness has improved since Valencia. He might have ran faster than 12:35 if he had worn vaporfly . Having said that more research need to be done comparing vaporfly and dragonfly energy return on the track

While we're on the topic of shoes, is there a reason that the "progressive compression" spikes used by some Adidas models fell out of favor? Seems like a solid concept to me: instead of using very sharp spikes that dig into the track surface and require the athlete to pull the shoe out the surface, the Adidas "progressive compression" spike "rides" and bounces off the surface instead of digging into it.

impossible to compare track racing with road racing!

my question is why did he wear the dragonfly instead of the air zoom victories? does nike's distance spikes actually do better than their middle distance spikes now? pretty much no pro ever ran with the matumbos; they always used the victories.

Last year there were not limitations for racing shoes on track. The first 3 athletes in WCh of Doha ran with spikes, and all of them had very good experience with racing shoes : Cheptegei (winner) used Vaporfly for bettering the WR of 15 km (41'05") ; Kejelcha (silver) used Vaporfly in his HM (Copenhagen 2018 and Valencia 2019) ; Rhones Kipruto (bronze) used Adidas Zero for the WR of 10 km.

If really it's possible running, on track, faster with Vaporfly than with spikes, why these athletes didn't run with Vaporfly (that time legal) ? Can we suppose the 3 best in the World are stupid, or that really spikes on track are faster than racing shoes ?

And, if this is the situation, WHY THE RULE OF WA DOESN'T ALLOW ATHLETES RUNNING ON TRACK WITH RACING SHOES WITH A SOLE MORE THICK THAN 25mm ?

A rule is a rule, but when the rule is stupid, is a stupid rule that needs to be canceled as soon as possible, in order to avoid injuries to the athletes, because to run distances longer than 10 km on track with spikes is the best way for creating problems for tendons and stress fractures in the bones of the feet.

Totally agree with you. Makes no sense for guys like Mo to be running the 1 hour record in streak 7s or something similar when vaporflys are available.

They had carbon plate wrote:

Cheptegei has admitted on twitter they had a carbon plate so it wasnt the standard DF. I think I've heard this 'who cares it's a level playing field' argument before but it's not. PEDs have become Performance Enhancing Devices. I mean athletics has now condoned this clandestine process to prototype shoes in races so we're back to an 'arms race' between teams/sponsors. They try to make us believe it is something we could buy but it isn't and probably never will be. Basically you have to knock off X% for any pro performance due to unfair advantages they have vs us punters.

You’ll have to accept that he does not have a carbon plate, and that I know what I am talking about.

Maybe they should all run barefoot, cut out the nonsense and let the best athlete win. Providing they are clean from PEDS.

All of those who think this spike did not significantly influence this time are idiots!

Read my latest paper explaining the teeter totter effect. The key is the stiff curved full length plate that provides an extra propulsive force to the heel during toe-off. The dragonfly is essentially identical to the vaporfly without the bottom layer of Rubber and Foam

Why?

1. The plate needs to be stiff not necessarily carbon fibre like used on bikes. There are other ways to make it stiff. Nike say PEBAX but Arkema sell CFRP PEBAX compounds that are injectable. CFRP = Carbon Fibre Reinforced Plastic. The reason Nike use this version of injectable carbon is that they can over-inject the metal receptacles for the spikes. adidas Rods in their shoe are also most probably injected.

2. The MONDO track surface is significantly more deformable than concrete. On the road the foam & rubber below the plate are required to

a) Protect the Carbon Fibre from contacting the ground - High Risk of cracking

b) Provide some ground adaptation and comfort - Carbon direct to concrete is not smart.

c) Some traction from the rubber.

The Dragonfly doesn't need any of these as you are running on Mondo

Anyway until someone proves that these spikes do not have a greater than 4% improvement in running economy on mondo then I believe that the main factor behind this record is the shoes not the athlete.

I think you got that backwards chief. YOU need to prove they have a measurable difference.

The dragonfly spikes have been used by pros for over a year in competition. If they had the effect you think, you would have seen it in the results - but you don’t.

FYI, a 4% time benefit would mean these shoes were good for over 30 seconds of improvement in the 5k. The record was improved by 0.3%.

U know nothing jon snow wrote:

I think you got that backwards chief. YOU need to prove they have a measurable difference.

The dragonfly spikes have been used by pros for over a year in competition. If they had the effect you think, you would have seen it in the results - but you don’t.

FYI, a 4% time benefit would mean these shoes were good for over 30 seconds of improvement in the 5k. The record was improved by 0.3%.

Exactly the record was improved by 0.3% using a technology system already proven to have a 4% Running Economy improvement on the roads (not 4% time). My point is that the mechanism of these spikes is essentially delivering the same benefit as vaporfly. Therefore some skeptical experts like myself will question the validity of this performance in terms of pure human achievement. This record has a mechanical propulsion element to it.

For more reading.

Benno "White Walker" Nigg

Salvitore Stitchmo wrote:

No they aren't and just for those who believe carbon fiber plates are new and magical - the Jasari had a carbon fiber plate/shank option back in the late 90's and the Vic elite (almost all editions of it I believe) had the same.

https://cdn10.bigcommerce.com/s-8va9tp6q/products/103/images/500/NZVEM1_5__92462.1453077152.1280.1280.jpg?c=2

Oh and the adidas Prime SP plate is made from carbon nanotube technology - both the new and old one from 2012

https://www.adidas.com/us/adizero-prime-sprint-spikes/B37494.html

So everyone just pour some ice water on their little hard "carbon fiber plates are unfair" stiffies - they have existed literally for decades.

@Salvatore - I agree with you that the argument regarding Carbon or no carbon is stupid as the material is not important. Stiffness & Curvature is important. Unless the plate is full-length, Stiff and with a pronounced curvature then it will have minimal benefit as it will not enable the "teeter totter" or see-saw effect. The curvature is what enables the transfer of force during toe-off to the heel. Your flat Vic Elite will not compare in terms of propulsion due to the lack of curvature and the extension to the heel.

This is not the first spike designed in this manner.

Sapel wrote:

This is not the first spike designed in this manner.

Key word being "designed". You are correct many spikes have been "designed" with carbon plates in the past. What is missing is the "engineered" part. This is the difference between something that is designed to look nice and light and feels good, and something that is engineered using the latest understanding of human gait and how to improve it by capturing energy that is normally wasted and returning it to the human at a useful point of the running gait to provide added propulsion. i.e. The curved carbon plates.

Class 1 Lever - This is why the Hoka shoes with flat plates don't work. They have no fulcrum. The curved shape is what provides the fulcrum.

This is exactly why the vaporfly and dragonfly plate are curved and are close to the ground in the forefoot and away from the ground in the heel. The ration is approx. 1/3 to 2/3 so the force applied during toe-off is amplified to the heel where it provides a propulsive force.

Benno, you are describing a rocker midsole. These have been around for decades. Just because you have not seen it utilized in a spike does not mean it is an issue. You are also forgetting the individuality of the human foot and now different feet of the same length have different fulcrum points, which is why not everyone can perform well in a shoe like the Nike Vaporfly road shoe.

And something we find in the biomechanical analysis of Cheptegei is that he does not heel strike to create the teeter-totter effect. He basically comes down quite hard on his forefoot and then pushes off. If you notice, he over-pronates quite extensively on his left foot. Remember, one of the big breakthroughs in biomechanical footwear design was engineering propulsion and enabling propulsion of the big toe. I can send you some papers if interested in this.

The Intelligence wrote:

Is this a picture of the shoe you are talking about?

Is there any mention of there being an 'air-bag' hidden inside of that foam?

Hidden Airbag :

Sapel yer talking pish. His point is nothing to do with rocker midsoles it’s to do with the plate. Hoka’s foam cannot Transfer force like a plate. Instead of posting why not spend ten minutes reading about it. Totally makes sense to me.