Epic REACT Mods and Carbon Fiber experiments

What type of carbon fiber inserts would you prefer?

  • I feel the need for speed... I'm only gonna use them for races, so who cares if they hurt a little

  • I'm all for compromise - give me as much additional speed as you can with all day wearability

  • Give me Cloud 9 - I want the float on clouds feeling all the time, who cares about my time

  • Size 9

  • Size 9.5

  • Size 10

  • Size 10.5

  • Size 11


Results are only viewable after voting.
I decided to run in my triple black ERs with the two holes and fastest carbon fiber plate to see if I could beat my 5K PR from yesterday in VaporFlys. My long term data shows about 4% faster than average times for my VFs, and anywhere from 4-8% improvement from my ERs with custom CF plate.

I did beat yesterday's time, but only by a little bit and my average HR was a bit higher, so I consider it a wash.

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Today's run was very different than yesterday's however. Yesterday's run in the VFs was very consistent throughout the whole run. Pace and HR curves vs distance were perfectly flat. Today's run in my ER with CF plate began 8% faster holding a HR of 160bpm. So I thought I would smash yesterday's record. But halfway through the run I felt the "propel you forward feeling" of the shoes go away. My pace then fell to 0% faster than average (4% less than VF) for the last half of run still holding a HR of 160bpm. Typically this is just due to muscle fatigue as my fastest CF plates need the muscles to load them up during each stride. But this time my muscles were not fatigued at all. The plates just went limp. I think I might have finally found the fatigue threshold of these springy plates after well over 100 miles of running and trail hikes. Not sure yet.
 
I got impatient and couldn't wait until the weekend to make some more CF plates - so I cranked out one pair over a long lunch hour. These are using the high tech CF I special ordered from Japan. Since I only have one size 10 mold, once they set, I put them in my shoes to cure, freeing up the mold for me to make the next pair this evening.

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I can't wait to try them out, but it takes 24 hours before I can sand them and 72 hours before the resin is cured enough to run in them. But I am skeptical this first pair will turn out right, as whenever I change materials, it takes several iterations to get them right again.
 
I am skeptical this first pair will turn out right, as whenever I change materials, it takes several iterations to get them right again.

Yup, they came out as limp as a soggy lasagna noodle. They look beautiful and fit perfect, but have zero stiffness or spring.

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I am really mad at myself for paying a small fortune to order special CF from Japan and ship it here, only for it to have no modulus. Why didn't I just read the datasheet? I did, it says "trade secret" in all the rows of the spec table. I think this was made as a cosmetic outer layer for CF layups, not a functional working layer.

Oh well, back to my previous CF. Fortunately I ordered some of that at the same time, so I can still make some more plates this weekend.
 
If first you don't succeed, yada yada yada. I made these two pair last night using my previous CF. I won't be able to try them out until Mon at the earliest, so looks like I'll still be using my old plates this weekend.

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Today I repeated last Sat's HM run. Last week I used my blue laceless ER with the hole in forefoot with no CF plates. Since my arch muscles gave out last week 10 miles into the HM, this time I decided to add my "floaty" plates to them. While my floaty plates do not add any speed or efficiency, I thought they might help support my arch and relieve some of the work of the arch muscles.

It appeared to work. HM run at Full M pace, keeping heart rate steady at 145bpm.

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Out of all the new carbon fiber plates I just made, one pair came out really nice. I probably should have given them 24 hours more to cure, but I couldn't wait to try them out. I took out my previous fastest old plates from my TB ER1s with the two holes in them and installed the new ones.

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I ended up setting a new 5K PR. My time was 5.5% faster than average with no plates, which is 1.5% faster than last two 5K PRs with old plates. TBH, my average HR was 5 more at 165bpm though. However, the biggest difference was in how they worked. My previous fastest plates required a modified running stride, and you had to "load" them up for max gain. However, these new plates did not require any loading. My natural normal running stride worked best, so there was no additional strain on my muscles/tendons. I was really happy with these plates. They are not as comfortable as my floaty plates, as they are very stiff to walk around casually in, but they felt relatively comfortable when actually running in them.

I now need to figure out what I did in this pair that worked so well and try to replicate it in another pair.
 
I cranked out as many CF plates as I could yesterday. My work and family life are both very busy, so it is not often the planets align and I have time to make shoe inserts. I'm headed abroad for all of Sept, so this is my last chance to make them.

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Since I managed to make one comfy pair of floaty plates and one fast pair of speed plates, I focused my remaining efforts on achieving the ultimate compromise plates - something in between the two. I'm not sure I achieved it, though. Most are still curing, but my initial impressions were not very good. Hopefully at least one pair will be a good compromise.
 
I cranked out as many CF plates as I could yesterday... Hopefully at least one pair will be a good compromise.

Out of all the plates I made, one pair seems to have come out as a pretty good compromise. I put them in my black IDs I wear for work and they were not as comfy as my floaty pair, and I didn't feel as much "propel you forward" as my fast pair. There is a chance they do neither well. I won't know until I run in them and get some data.

I'm taking today off running as the ball joints in my hips are inflamed and I don't want to risk injury, but I'll wear the "compromise" pair to work today and run in them tomorrow.
 
Wore my latest best "compromise" plates all day yesterday at work in my TB laceless ER2s and for this morning's run in my TB ER1s with holes in forefoot and heel:

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They were terrible. Less comfortable than my stiff fastest plates and slower than using no plates. After staring at the shoes, insoles, midsoles, and outsoles, and looking at slow motion video I took of the shoe in stride, I had decided to try moving both the heel and forefoot flex points forward. This was a mistake, as both felt wrong when walking or running.

I've probably got enough time and materials to make one more attempt at a compromise plate, and then I'll just give up and make one more set of floaty and fast plates as spares.
 
I like my new fastest CF plates so much I couldn't resist trying to make a pair for my Turbos. As I said before, my Turbos are my slowest shoe by a wide margin, but they have so much pop I think they could be my fastest shoe with the right plate design.

I tried my fastest Epic plates in my Turbos for just a few steps. They do not match the shape of the shoes, so I did not want to risk damaging my favorite plates. It felt like the design should work for my Turbos. The problem is I do not have a mold shaped like the Turbos. So I used a thinner in the resin, used the Epic mold to load the CF with the thinner resin, then pulled them from the mold wet and laid them inside the Turbos for final shaping. This hack yields a much worse plate and they look pretty ugly, but the function should be about the same. It is also risky, as the first time I did this earlier this year, the plates would not release from the shoes and I ended up trashing my first pair of Turbos (OG Black/white). That was a very expensive mistake as I paid retail for that pair of Turbos!

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With all my shoes filled with various test plates, my only shoes available for this morning's run were my VaporFlys. I didn't get any valid time data though, as I had a break in the middle of the run.

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My latest plates will be sand-able this evening and ready to run in this Sat morning.
 
I'm happy to say my compromise plates came out good. Just guessing from a quick run around the block, I think they will only be good for 2-3% gain, and they are comfortable, but don't give the float on clouds feeling the floaty plates do. But they feel good enough.

My new Turbo plates also came out good. They feel bizarre in the Turbos. With this fast CF plate added, the heel becomes less stable and the shoe wants to throw you forward like hitting off-center on a trampoline. In other words, they feel just like Vaporflys now! The Turbos have so much cushioning, you can't really feel the plate working like you can in the Epics. It feels really fast... I'm guessing it might match the VFs? Hard to even guess at this point.

I figure I will run my morning loop in the new compromise plates for some data tomorrow before work, and then do my longer Saturday run in the Turbos with fast plates. The Turbo plates need more time to cure and I want to try them on the longer run.

So now I have the following lineup of shoe/plate combinations. I'm very happy with how everything turned out. I have plates for my Turbos to help speed them up a bit on recovery days. I have my fastest plates for my running beaters that I use for dirt trails and racking up the mileage along with two holes to let the midsole flex with my fastest plates. I have work shoes with compromise plates. Why not floaty plates? When on business travel and I'm wearing a heavy backpack and have luggage in each hand, the extra support is welcome. I don't want holes in my work shoes as I frequently walk through standing water. And my super comfy leisure shoes with forefoot hole and floaty plates for extra comfort. I actually sigh every time I put my blue leisure shoes on - the most comfortable shoes I have ever worn.

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As planned, I did my morning run in my latest "compromise" CF plates in my TB laceless ERs I use for work. At first I was panicked as there was no improvement in pace, but as the REACT foam warmed up over the first mile my pace gradually increased over my no plate average to about 3.5% improvement. These shoes do not have many running miles in them and the foam was very stiff at first.

I'm not sure why but the arch felt slightly in the wrong place on both feet - maybe the plates slipped in the mold a bit. I noticed that going down steep hills the improvement completely disappears, while going up steep hills the improvement increases slightly. None of my other plates have done this. Also, I typically land midfoot when my feet are aligned with the forward angled line of my body. But these plates seemed to benefit from letting my heel contact a bit earlier in my stride. Overall I am happy with these plates which is important as these will see the most use, as they will be in my work/travel shoes.

I can't wait to try my new Turbo plates out tomorrow morning on a long run.

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Back from my morning run with the Turbos and new plates. They certainly felt fast, like having trampolines on your feet. Unfortunately the data says otherwise. They only matched my lifetime average without plates, which is still faster than stock Turbos which are about 4% slower, but it is still a disappointment. While they were about 3% faster for same stride, they were not more efficient - that pace made my HR gradually peak out. Holding a steady HR of 155bpm yielded a pace equal to my average pace with normal shoes and no plates.

This highlights why I take so much data, and wear 3 separate monitors running separate apps. You can't just go by feel alone. My fastest plates in my ER1s do not actually feel any faster, but the data consistently shows 4-8% improvements.

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I'm not sure why but the arch felt slightly in the wrong place on both feet - maybe the plates slipped in the mold a bit.

Unfortunately I figured out why my most recent plates are slightly out of spec. I was making a spare pair of floaty plates today when I noticed there are ridges of resin built up in the mold. I use plenty of mold release, but somehow resin has built up in several places. These ridges of resin push the plates slightly out of position. I tried to see if the resin could be snapped off, but it is glued firmly in place. I tried sanding, but the mold is actually softer than the resin, so it wants to sand first. So it looks like my mold may be shot. I made two spare pairs of floaty plates anyway, and I'll see how they feel in my shoes. I've run out of vacuum bagging film so I think I'm done making plates for now.
 
Since my Sat morning run was shortened by the Turbo poor results, I felt like doing more than my short Sun run, so I hiked the local hill climb again. I wore my TB ER1s with forefoot and heel holes and newest fast CF plates. They are simply amazing. No matter the hill grade, surface, or pace, they supported my feet, gripped like mountain goats, and sprung forward like I was wearing a rocket pack. I love these shoes.

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Took a rest and recovery day yesterday, as my hip joints and knees were a bit sore from the hill hike. So this morning I thought I would do a fast 5K run. I ended up 2% off pace of my PR, but I got carried away during the first half and let my HR jump over 170bpm, which built up lactic acid in my leg muscles, so they burned the whole second half of 5K run.

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This morning I did another fast 5K run in my Vaporflys. I wanted to see the best I could do in my VFs and get some more data on them to compare to my own plates in ERs. This time I modified my running form a bit, trying to maximize my "hang time" after each toe off. I did slightly beat my previous PR set in my ERs with fastest plates. What amazes me about my VFs is how consistent they are throughout the run - all my data plots (speed, pace, cadence, HR, etc) are perfectly flat.

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I did notice something new with my VFs. On my walk back after my run, both my right and left shoes were squeaking with each stride. They have never squeaked before, that I have noticed. I didn't go through any water and I did not have sweaty feet.
 
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For those who have PM'd me, yeah I'm still here. Sometimes you gotta stop obsessing over shoes and just run in them. I'm out of carbon fiber and my mold is shot so I've just been running and taking data.

I've removed the CF plates from my Turbos. The CF plates made the Turbos hard on my muscles and tendons, and I prefer them as a slow recovery shoe. While the Turbos might be slow, they are very plush.

My favorite and fastest shoes are still the ER1s with two holes and stiffest CF plate in them. My average times in them are about 5.5% faster and they are very comfortable and supportive. I've noticed a new wear area on the heel since drilling the heel hole, in red below. I've also noticed the heel hole always picks up rocks, in blue below. The heel hole feels great, but I don't think I will do this mod to any more shoes, given these two problems.

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By popular request, here's my take on the new Infinity Run.

First off, to try and sell the shoe as magic that will prevent running injuries is pure Marketing hype. No shoe will prevent or even reduce running injuries.

1. Where I put the hole in the forefoot for extra flex of the foam, the IF outsole is most solid, the opposite of what I do. However, it might be correct for this shoe - won't know until I put 100 miles on a pair.

2. The TPU heel clip is bigger in the IF. In my ER experiments I found the TPU heel clip does nothing at all. I have removed it from ERs and compared with and without, and I think all it does is protect the top edge of the REACT foam so they can create an overhang. So making it larger does not increase stability, though increasing overhang will.

3. The IR has more forefoot rocker designed in. One of the things I like most about the ER is it has the perfect amount of rocker, and then when you enter toe off, the shoe flexes at the foam/rubber line of the outsole and grabs the ground with nice toe splay. There was no need for more forefoot rocker.

4. The IR is supposedly wider. I liked the "fit like a glove" feature of the ER. It let me leave the laces loose or even go laceless. I agree the ER was too narrow for some people. They should have just offered wide sizing options, like with the Pegasus. My worry is that people with narrow or normal feet will now have to cinch down the laces tight to keep the shoe in place.

5. Reviewers are mentioning the IR has a design that "hugs the arch". I'm not sure what they are referring to, so I will have to wait until I try them on to comment.

6. The IR shoes are heavier than the ERs.

Overall, at this point, I'm not happy in the direction Nike has gone with the IR, but TBH I haven't even tried them on yet. I'll probably get a pair and after 100 running miles I'll comment more and maybe even try to make a Carbon Fiber plate for them. For now, though, I'm stocking up on ERs, especially laceless ERs and Phantoms.
 
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Red: I've circled where the most solid part of the forefoot outsole is. This is the exact spot I core a hole in my ERs. This the most critical spot for the foot, the single spot all the forefoot muscles intersect and must flex. This spot should have been relieved with gaps like in the heel.

Blue: Note this is the only spot where there is an end-to-end gap in the outsole. I like this very much. This is the exact spot the outsole must bend as weight is transitioned from heel to forefoot landing.

Green: While I like the outsole relief areas, as they will help traction and flex, the gaps are simply too big. For a given runners weight, the area of the outsole determines load. It is pounds per square inch (or kg per square centimeter). Think of the runner's heel strike, and all the weight pounding on the outsole. These huge gaps have doubled the pounds per square inch, as they reduced the area by half.

Pink: This is all TPU reinforcement. The ER2 made the heel clip smaller than the ER1. This goes the opposite direction, and not only makes it bigger, but extends it all the way past the mid foot. Nike did a similar thing with the Rise and Phantom. This is way too much heel lockdown and will prevent the midfoot from flexing correctly. I'm not sure where or when Nike started thinking a rigid back half of the foot is a good thing. The entire foot structure must be able to flex. Like ER1 and ER2.

Black arrows: In the ER1 the outer lace reinforcement panels were a single connected unit per side. On the ER2 they added one split in the middle to allow more top of forefoot upper flex. In the IR, they have gone further, adding two more gaps, so each lace hole is individually reinforced. This is a very good feature, assuming the inside reinforcements are also individual and not a huge panel of plastic. The flex of this portion of the upper is very important to the running stride, which is why I prefer the Phantom for running, as it has nothing here at all but Flyknit.
 
Another change in the IR versus the ER1, ER2, Rise, and Phantom is a switch from a variable weave flyknit to a even mesh like weave. It might still be a flexible knit structure, but it is evenly woven.

Compare the IR here:

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With an ER2 here:

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The main advantage Nike had over other brands' knit uppers was the variable weave. Recently Nike appears to be abandoning true flyknit in favor of high tech meshes.
 
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I have been asked how I can run in laceless shoes like the Phantom, and why would I want to do so. What about "lockdown"?

I started running laceless purely by accident. I showed up to a road race wearing my laceless ERs I used as casual slip-ons, and then realized I had forgotten my running shoes (Vaporflys). It was either run in my laceless shoes or go home, so I ran the race being careful with my foot form. Afterwards I noticed my feet felt fresh and the next day I noticed I had no foot issues at all. So I started working my laceless shoes into my daily runs. Now I swear by them.

So what is happening? I've been trying to figure it out. I have come to the conclusion that the instep area of the foot has the arteries and veins that feed blood to the foot. Almost all running shoes have "lockdown" designed in which squeezes this exact spot on the instep of foot. Nike has Flywire, Adidas has their plastic cage, etc. Runners have gotten used to this part of the foot being secure.

I found the following diagram of foot anatomy online and have circled the critical area of instep that is important to blood flow, which also happens to be the area that gets squeezed in most running shoes. I've also pointed to a couple of important pinch points that should not be squeezed off.

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I'm not a foot doctor or expert, so I can't say for certain this is what is happening, but ever since I have changed to shoes that do not squeeze my instep, my feet have felt very fresh, even after a Marathon. While my favorite shoe is the laceless ER, I have replicated this effect in other shoes that I have either uncaged or removed laces from.
 
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