Tested the 4% with several clients; for some it works and for others it doesn't. One client tested a used 100+ miles On cloudflyer, new Brooks ravena, new NB 1500v5, and new 4%. The used On, new Brooks, and new 4% all had very similar impact forces and force rates. The new NB1500v5 had a force rate about 68% lower than the other 3 shoes. Important to note the 4% had the lowest impact force and the NB had the highest impact force (approx 10% diff), but the 4% had a significantly higher force rate for the client (NB uses medial post at heel to midfoot). Also, the posterior heel flare of the 4% isnt ideal for heel strikers with a high foot angle at contact. It creates a longer lever arm which tibial muscles need to eccentrically control when lowering the foot to the ground.

Is this tested with force plates? It's great that people are doing this sort of thing and thanks for sharing. Do you think that there is consensus about how this sort of information would inform an individual runners shoes choice?

My guess is that with the majority of modern running shoes they aren't simply better or worse but suitable or unsuitable for a runners specific issues - injury history, running style, etc.

Yes, the 4% (and the little-bother Zoom Flyknit) are easier on the joints than most shoes, especially for long runs. That said, both versions, and esp. the 4%, are narrow and might wreak havoc on your toenails on the outer toes.

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<The Dew Abides>

I'm not much of a runner or expert on running mechanics, but we just launched a handlebar tape today based on a combination of Pbax and TPU and I found the test results and behavior of the foam to really be exceptional throughout the design process. It started when I bought some React running shoes right after they came out and actually enjoyed running in them. A deep dive with the foam manufacturers was eye opening not just into what these particular foams are doing, but also for a look at the level of tune-ability and design flexibility they give the engineers compared to previous tech.

Just as the Strava running data proved out that the shoes were faster, I wonder if that platform could be used to crowdsource some injury data? I know that I certainly run with less muscle and joint pain in these shoes than anything previously, but of course n=1

https://blog.silca.cc/...-generation-bar-tape

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http://www.SILCA.cc
Check out my podcast, inside stories from more than 20 years of product and tech innovation from inside the Pro Peloton and Pro Triathlon worlds!
http://www.marginalgainspodcast.cc

Did a 7 km race three days ago (of course faster than to be expected with conventional shoes) and did not experience any soreness which I normally would expect. Ran yesterday in training as if I had not done the race three days ago. Fantastic. It makes me feel to use it as training shoe too. Although as the shows seem to wear quickly I also tend to use them not too much.

They have a strange clicking sound when you walk with them on tiles. I thought they were already desintegrating, but a mate of me had the same issue. Probably normal.

Full Discloser: I do research for the running shoe brands and this is a rather big topic.

Comments and Questions
1. There weren’t 6,000 pairs of Vapor Fly 4%s in Boston. That would equate to 19% of all running shoes in the race and that’s just not possible. That said, there were a bunch.
2. I talked to a guy after the race. He’s a regular Kona and Boston qualifier says he doesn’t train for the marathons, just runs them. Didn’t want the Vapor Fly to work. Tried a pair and couldn’t believe how they felt. Says before it would take him a week to recover from a marathon like Boston. Now in the Vapor Fly he can run the next day.
3. It’s not possible for a shoe to be the only answer to this. There has to be biomechanics involved too. If you are traditionally a hard runner meaning your general footplant is hard or forceful, a shoe can take some of the force out of you but probably not all of it. You will need to absorb it. If however you land softly as you run the shoe can be of service in removing more of the shock.
4. There are two aspects of the shoe’s materials at work here. First is the Carbon Plate. At Zoot we used Carbon fiber in almost all of the shoes we built. We used three basics designs. All had a forefoot finger that ended under your first metatarsal head. Athletes told us regularly that they felt faster in our shoes and some reported a reduction in shock. So the carbon plate in the Vapor Fly and the Zoom fly and the Hoka Carbon Rocket or the Carbon X will definitely give you that feeling of running faster and the carbon plate just like your carbon bike will dissipate shock. The Vapor Fly however also has a pbax foam midsole. It’s by far the most advanced (and expensive) midsole foam. Only 2 companies (Nike and Reebok) use it today but there is one more on the horizon. Every foam is graded on it’s ability to absorb impact and “return” energy. Compression molded EVA is good, Cmeva with a rubber mix is better. Boost started the latest revolution in foam and it was the best we had ever seen. Now the same Boost material is available at Brooks and Saucony. Nike developed React foam which is their blend of relatively the same blend as Boost. Then there is Pbax and it sets a completely new standard against the Boost material. It’s as soft but’ it is much more resilient. It’s what gives you the snap you feel running in the 4%. You know this if you’ve run in the Pegasus Turbo or the Reebok Float Ride Fast. They have that snap and they too use the Pbax midsole.
5. Based on my research the Vapor Fly 4% is the best at reducing the aches from pounding out a marathon to date. It won’t work for everyone but it’s the thing I hear most about the shoe. I actually hear less about running faster. The funny thing is, Pbax foam has been around for a long time. It’s not a new blend of foam. What Reebok and Nike learned is how to mold it into a midsole on a relatively cost effective method. It’s a big investment for any brand to get started using Pbax but I think based on these results it’s going to be really difficult for the brands to hold back spending the money.

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Dave Jewell
Free Run Speed

One of my all-time favourite shoes: the Zoot Race 2.0. I searched for years for an identical shoe. I never succeeded, even among the Zoot lineup. Only the VF4% tops them in my view, despite being a totally different kind of shoe with something like 7mm more drop and a troposphere more stack than the Race 2.0. I'm still pissed at Zoot for getting rid of that work of art.

DM

Thanks Dave for such an informed post. Appreciate you taking the time.

Another n=1 study response. 58 years old. Train in Hoka’s and previously raced in them. Bought the Nike 4% Vaporflys a few weeks ago. A few short training runs in them, before racing in them at IM Santa Rosa. New IM run PB at 3:59. Typical “everywhere” IM soreness after the race, however, the legs were not as beat up as usual, and using stairs was uneventful. Granted the run course was flat though. Plan moving forward this season is generally train in Hoka’s, race in the 4%’s

Leg yes, feet no.

I have found the same effect with the Reebok floatride run fast at $100 less than the 4%. They both use the same foam.

Been away from this forum for a few weeks. Am mid 50s. Bought the VF4%. Cut 9% off race time. Can't imagine EVER racing in anything else. They are the Fountain of Youth. Like the pool in Cocoon.

Just curious, to folks racing in the 4% for tris. Are you using elastic laces (they seem to cut into my feet given shoe is so thin), or do you find yourself able enough to get the shoe on and off tied with regular laces given the upper is so flexible? I'm worried that they go on fine with thin socks, but I'd have issues wearing them sockless.

so I've done the online research and it seem pretty indisputable, so I ordered them today, after trying on some Nike's locally, to get sizing for this brand down to a reasonable guess...

the NY Times article
https://www.nytimes.com/...fly-shoe-strava.html

who believes the Times..

Strava data is more impressive. I like that they say the strava runners are 'an enthusiastic bunch'-HAHAHAHA!

I'm convinced.

I did my first 70.3 with elastic laces not much tighter than the compression that the flyknit creates and found on descents that were a little steeper my heel was slipping about and it was pretty sketchy. At me next 70.3 I just put a lace locker on and after putting the shoe on I pulled the laces out a few inches and they were fine. I was wearing socks.

All I can say is I think the shoes some bearing. My best 70.3 run was a 1:27 and my last race I don't think I was in as good form albeit was a slightly easier run course I ran a 1:25...

I'm sort of confused by what you mean with respect to the "Lace Locker?" Do you mean you just used the regular laces and one of these? https://www.lacelocker.com/ I'm not sure how that would help. Seems like it just keeps laces from flopping around if they accidentally untied.

Or do you mean you used regular elastic laces and just tightened them down a bit after putting the shoe on?

Either way, I'm planning to do some experimenting of my own, but would be nice to cut out a few cycles of failed experiments and blistered feet.

I pretty much always race in socks at 70.3 distance and up. I use the thin but double-layer Wright Socks and roll them on like a condom--takes maybe 2 seconds per foot and I NEVER have to slow down due to chafing/blisters.

I'm using the Xpand laces. They are a ribbon style and if you take the time, they lay flat across the top of the shoe (and your foot)

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TEAM F3 Undurance

Thanks. I'll give them a try.

I'm also getting some heel slippage in this shoe. It's like the ankle collar isn't high enough. I have a narrow heel though and usually resort to adding an extra loop to cinch my heels down. That's not really possible with this shoe though. So I've resorted to making an extra lace hole through the mesh, but I do wonder how viable that is longer term.

These are the laces and locker refers to the spring loaded device that locks your lace once you pull it shorter as you get with the laces.
https://www.runnerinn.com/...BwE&gclsrc=aw.ds

I find with the Zoom Fly Flyknits that there is enough give with the Flyknit that I can get my feet in using the original non-elastic laces with the locks taken from a set of elastic laces.

I just used them for a sprint tri. Original laces and body glide my feet slid right in.

I have used 4% for the first time this year and set PB's from mile up to HM distance. They are bouncy and fast. I dont train in them just race. I mainly train in zero drop shoes or Nike Zoom Streaks.

However - the 4% kill my 2nd toes. I have Morton's Toe so 2nd toe is longest. After the HM I had to walk around in bare feet after the race albeit I didn't feel the pain until around 20k. I think a marathon would have been seriously problematic.

Anyway, I bought some Next% one size up, and used them on the track the other day for around an hour running various tempo speed intervals. Again, big toe pain afterwards. I had to take ibuprofen to alleviate it.

Anyone have any suggestions as to why its worse with these shoes and of any ways ( lacing, insoles? ) to alleviate?

Not sure if this was posted in another thread but it seems that Nike (Brett Kirby) confirmed that the vaporfly reduces muscle damage and thus speeds recovery between training, allowing those who wear them in training (blasphemy!) to train hard, faster, and further.

Of course the author notes the grains of salt, which are important, but it is interesting.

https://www.outsideonline.com/...n-plate-presentation

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808 > NYC > PDX > YVR
2024 Races: Taupo

I don't train in them so I can't speak to the daily thing.

But there is this 10 mile race that is hilly as hell up here. Every other year it seems to be in our USATF - New England Grand Prix so I sorta have to run it. It usually beats the bejesus out of my legs.

This year I wore the 4% in them. Not only did I have a surprisingly fast time, but when I was done, it was like I had hardly run at all. Not even the slightest bit of discomfort. It was weird. . At this point in my life I think I'd wear them even if I was certain it meant my time would be significantly slower.

Anyone have a report on the speedier recovery compared to the next %?