Sunday, May 19, 2019

UPDATED Hoka ONE ONE Carbon X Nine Tester In Depth Review: Carbon Dating—the next shoe with a carbon plate. How does it stack up?

Article by Sam Winebaum, Derek Li, Jamie Hershfang, Jeff Beck, Peter Stuart, Dom Layfield, Mac Jeffries, Michael Ellenberger and Hope Wilkes

Hoka ONE ONE Carbon X ($180)
Update: Derek Li and Jamie Hershfang offer their Carbon X perspectives in this update to our earlier review. Derek is a 2:41 marathoner from Singapore. Jamie participated in the Project Carbon X record attempts and was on the team that set an unofficial mixed gender 10 x 10 km world record.  Her full race report is here
Sam: The Hoka Carbon X was “introduced” on May 4th at a special race in California. Several Hoka elite athletes chased world road records in the X with Jim Walmsley setting a new world 50 mile record. 

And the Carbon X was a totally appropriate running shoe for the quest. It is a light (8.5 oz / 241 g), maximally cushioned (32mm heel / 27 mm forefoot) long racer and trainer with a propulsive carbon fiber plate. 

Ten of us here at RoadTrailRun have now tested the Carbon X and offer our varied perspectives on this unique new shoe in our multi tester review here.

“The Carbon X embodies everything that has made HOKA such a popular and quickly-growing brand,” said Gretchen Weimer, Vice President of Product at HOKA ONE ONE. “Combining premium performance engineering, an extraordinary weight-to-cushion ratio, and a user-friendly geometry and ride, this shoe is designed to empower athletes the world over, and to help them feel like they can fly.” ​
The carbon fiber plate is embedded above the thick rubberized foam outsole (the first line up at the change in color from white to blue in the picture above). In addition to the carbon plate, X features an aggressive Metarocker and Hoka’s active foot frame construction which embeds the foot in the midsole. The outsole is a 

The Carbon X is  available at with other select retailers coming June 1st. It can be pre-ordered at RoadRunner Sports and Running Warehouse at the links at the end of the article. The first release color, the same for both women’s and men’s sizing is the blue and white above with more colors to drop in July and August 2019.
Its thick, full contact rubberized foam outsole has proved exceptionally durable for me with over 75 miles on the counter to date.

The stiff carbon chassis provides stability, an easy going rocker powered ride and a fairly gentle non harsh propulsive feel at all paces, except maybe very fast paces for me given the high stack of soft foam, low drop and the rubberized foam outsole. 
The upper is a thin, single layer engineered mesh with a short stretch bootie.

I tested a Carbon X prototype, top to bottom all white, for more than a month before release  Nobody, literally  nobody, has noticed them or asked a single question about them. Cool camouflage!
I have run more than 75 miles in my all white prototype, including a 20 mile Boston tune up race, easily done at 8:04/mile pace with minimal soreness the next day. and none during, and the marathon itself, a disaster for me due to allergies and in no way due to the shoe.  

Many will likely immediately seek to compare it to the Nike Vapor Fly.  While they share carbon plates and lots of cushion for a racing shoe, they are very different beasts. Whereas the Vapor Fly can be thought of as a racing shoe that can be trained in, the Carbon X for most will be be a training shoe that can be raced. Incredibly well cushioned, in a softer and slightly bouncy way with in the mix the firm carbon fiber plate pop, it is very broad and stable on the ground. 
Watch our YouTube Review

The RoadTrailRun team has now extensively tested the Carbon X and shares varying perspectives in our multi tester review.

Estimated Weight USM9: 8.8 oz / 249 g
Production Samples
US M8.5:  241 g  / 8.5 oz
US M9.5: 250 g / 8.82 oz
US M10: 260 g / 9.17 oz (as supplied, measured on calibrated scale)
US M10.5 274 g/ 9.6 oz 
Official Stack Height: 32 mm heel / 27 mm foretoot, 5mm drop
Dom: Measured stack height: 36 mm heel, 26 mm forefoot.  (Hard to know where to measure in a shoe as heavily rockered as this.)
$180. Available May 15 at June 1 at other select retailers.

Tester Profiles
Derek is in his 30’s and trains 70-80 miles per week at 7 to 8 minute pace in mostly tropical conditions in Singapore. He has a 2:41 marathon PR.
Jamie is 26 years old. 1:19 half marathon PR. She has run 3 marathons, current PR is 2:49, and is  training to qualify for the 2020 Olympic Marathon Trials (2:45) will attempt at Grandmas Marathon next month. Typically runs 90-100 miles per week and works at Fleet Feet  She trains in the Nike Pegasus Turbo and usually races in the Vaporfly 4%.
Michael is his 20’s and is a 1:07 half marathoner. He runs 50-60 miles per week, generally in lightweight trainers or racing flats at around 6:00-6:30 minutes/mile.
Sam is the Editor and Founder of Road Trail Run. He is 62 with a 2018 3:40 Boston qualifier. Sam has been running for over 45 years and has a 2:28 marathon PR. These days he runs halves in the 1:35-1:41 range and trains 40 miles per week mostly at moderate paces in the 9 minute range. He is 5'10" tall and weighs about 165 lbs.
Dom 47, trains and competes mainly on trails in Southern California running about 3000 miles and 500k ft of vert per year.  In 2017 he was 14th at Western States 100 and in 2018 finished 50th at UTMB and 32nd at the 2018 Los Angeles marathon in a time of 2:46.  
Jeff is the token slow runner of the RTR lineup as such his viewpoints on shoe and gear can differ from those who routinely finish marathons in three hours or less.  Jeff runs 30 miles per week, both roads and desert trails in North Phoenix, Arizona. He has a PR's of 4:07 marathon and 5K at 23:39 
Mac is a former collegiate defensive lineman who runs to fill the competitive void left after school and to stay in shape. He is in his late 30s, runs 50-80 mpw, and at 6’3”, has come down from his playing weight of 275 lbs to a steady 205 lbs for the last 10 years. Jeff’s PRs are 19:30, 1:33:xx, and 3:23:xx; he also teaches and coaches XC & T&F.
Hope is in her 20’s and after several ultras is now more on the road. She has a marathon PR of 3:47. She trains about 50 miles per week with many of her runs in the (broad) 8:00-10:00/mile range. She is happy to hit 7:30 miles on tempo days.
Peter lives in Austin, Texas and is a sub 3 hour in the marathon in recent years as well as a 1:25 half marathoner.
Sam/Peter: The most runnable, fun and comfortable, maximally cushioned road shoe I have tested to date.
Sam/Dom: Excellent long run, heavy mileage, and most paces daily trainer.
Sam/Jeff/Dom: In no way a mushy chore to run despite the supreme cushion. Enough midsole squish to make shoe comfortable for long miles
Sam/Jeff:/Peter Very stable platform for such a big stack height
Sam/Jeff/Dom//Peter: Very comfortable, breathable, lightweight and roomy upper
Sam/Peter: Very durable outsole; very minimal wear from the rubberized foam outsole at 70 plus miles.
Dom/Sam:  Noticeable carbon plate pop.
Dom/Jeff/Sam/Peter:  Much more stable on uneven ground than Nike VF4
Michael: Exceptional construction; integrates the signature Hoka “rocker” with carbon in a way far superior to the previous Carbon Rocket; comfortable upper and dynamic cushioning that can work for 5K race to 3-hour training run

Sam/Peter: Very low volume, very narrow feet may be challenged by the fit, especially at mid oot and heel.
Sam/Peter: Heel hold down low could be improved.
Sam: Carbon plate pop somewhat muted by soft midsole and outsole, 5mm drop and flat placement of the plate.
Sam/Jeff/Peter: Not as dynamic and responsive as I would like at faster than marathon to half pace racing
Sam/Jeff/Peter : There is a lot of substance in cushion stack and platform width but weight is up there for the racing game due to the use of an EVA foam and not an exotic super foam, albeit a light lively flavor of EVA
Mac: the feel is a little mushy for my taste, but that may be personal preference (or an effect of my 200lb frame as opposed to Sam’s svelte figure!)
Jeff/Peter: Ultra stiff CF plate can lead to some post run foot pain
Michael: About as stiff as possibly tolerable, and a couple ounces heavier than I would assume we’d find in a “racing flat”.
Peter: Unlike the Vaporfly they don’t “want” to go fast. For me a little too heavy and slow for a race shoe and a little too stiff and punishing for a daily trainer. Feel a bit beat up at end of longer runs.

First Impressions and Fit

Derek: I really like the clean look of this shoe. I’m a big fan of white and blue, and this color, together with the Reebok Floatride Energy, are my two favorites of the year so far. The shoe feels lighter than the advertised weight so that’s always a good start. Initial step in feel was excellent. Very simple unstructured upper that wraps the foot well. I didn’t need a lot of lace tension to get good lockdown. Fit-wise, it is definitely true to size for me. It is fairly wide across the mid-foot so people with low arches should have no problems. That said, shoe volume is on the lower side by Hoka standards, closer to the Mach 2 and Clayton than the Clifton.

Sam: The initial fit with my white prototype's glued in thin sockliner was a challenge at half size up from my normal.  Hoka sent along a more conventional, albeit still thin pre production sockliner. Removing the glued in sockliner and substituting allowed me to run and race with Salomon Long Run socks (medium thickness) with their silicone foot strips with no issues, zero blisters, irritation or pressure, ever. 

I now have a production pair in my true to size 8.5 with a glued in non flat sockliner and fit is much improved, although I still notice a touch of heel slip. Most with medium width to wider feet should go true to size. Very narrow low volume feet should consider sizing down a half. 

The upper is very thin, pliable and soft with no overlays. It is similar in texture to the Reebok Floatride Run Fast but a bit more pliable. It is completely unlined whereas the Reebok has a thin liner.

Those expecting a locked down race shoe fit will not find it here. Soft, roomy, but well enough held, this is an upper designed for long distances on the road in hot and/or wet conditions. The fit was comparable to the very first original baby blue Vapor Fly, albeit here we have a thinner more pliable (and breathable) upper. Later VF such as the Obsidian had a snugger mid foot and the Flyknit snugger yet. Narrow, very low volume feet may be challenged but with a thicker sockliner or socks or potentially sizing down a half most should be OK. Note there is also no toe bumper or stiffener whatsoever upfront beyond a very pliable underlay
Peter: This is the year I’ve finally been able to love some Hokas! I’m a big fan of the Rincon and was pleasantly surprised to get this carbon plated beauty in the mail. First impression is that it’s super stiff, good looking, a little heavy for a race shoe--and I’m wondering where they fit in the Hoka ecosystem. First thoughts: Love the upper, a little worried about the longevity and grip of the outsole. They fit true-to-size, but have to lace them down a little bit tight to get the foot held properly. The heel slippage isn’t bad--it just takes a second to get dialed in. As far as fit goes, gone are the days of Hoka arch blisters--the upper fits my foot well, provides enough support and feels great. Both the Carbon X and the Rincon have really breathable uppers. Will be great summer shoes.
Mac: Full disclosure: I have never worn a Hoka I didn’t eventually hate. Too much stack, too soft, too expensive… the Carbon Rocket was a step in the right direction, but the rocker sole didn’t work for me, and I eventually returned them. That said, I was intrigued by these: the super-secrecy, the catering to the Ultra market, the carbon plate, the size 14… and what I ended up with is what is by far my favorite HOKA-which isn’t saying a lot, but these are legitimately great shoes.
I received the production model, so no “Keds White” like Sam. My first impression was, “Wow, that is a lot of shoe.” Then, I picked it up. “Wow, that is a lot of lightweight shoe.” You folks with dainty size 11s may never get to appreciate what it is like holding a shoe this size and have it feel almost weightless. Yes, it is a full 1.9 oz. heavier than the VF4%, but consider this: it is a full 1.5 oz lighter than the Saucony Freedom, and it has !8mm! more foam (adding forefoot and midsole stacks)  AND a carbon plate in there somewhere. This is a shoe meant to go long, get there quickly, and protect you along the way. 
Fit is spot on, with maybe a touch more volume than average (a nod to swollen feet during ultras, no doubt) and an ample toe box (that is from a toe-box snob).

Jeff: My first impression was intrigued, and a little disappointed. Intrigue for the obvious reasons, and disappointed because the Hoka Rincon was so well cushioned (and lightweight) and while this shoe was obviously very well cushioned, at just a hair under 10 ounces for my 10.5 it was light, but not that light. Luckily, these are running shoes meant to be run in and not just weighed and photographed, so my disappointment only lasted until I started putting miles on the shoe. More down below on that, but for the fit, I found my true-to-size 10.5 to be perfect. My foot is slightly higher than normal volume, and this shoe worked very well, but in a way that I’d imagine most feet would fit well in this shoe. Unlike the Vaporfly, which I’m sure is going to come up a lot in this review (another high volume high technology high hype carbon fiber plated shoe? Hard to imagine), you don’t need to have a supermodel thin midfoot to fit into the Carbon X. Normal shaped feet will work just fine, and even slightly wide ones too.
Michael: First impressions were positive, if surprising. I had suspected the Carbon X to be soft, for whatever reason, but even in lacing it up it’s apparent that is not the case. In fact, the Carbon X is stiff, more so than just about any shoe I’ve tried in recent memory. My 8.5s fit perfectly - snug enough in the heel to avoid the slippage issue many of us encountered in the Carbon Rocket, wide enough in the midfoot to accommodate all sorts of foot shapes, and low-profile enough in the toe box to really feel like a racing flat.

Hope: I was headed out for a run in different shoes when I got the package notification for my pair. Ran to get them. Paused long enough to take a photo to capture the weight. Slapped them on my feet and was *so hyped* that I flew out of the gate  way, way too fast for my assigned easy miles. “Time to fly” indeed! The Carbon X feels different from other Hokas I’ve known — in a good way. But I won’t get ahead of myself. Suffice to say that these feel like true long-distance racers: loads of cushion, a barely-there upper, and light enough to not overburden tired legs.

Dom:  The Carbon-X seemed a strange beast upon receipt, but somehow makes perfect sense in retrospect:  it’s a Hoka-ized Vaporfly -- maximal cushion married to a carbon plate.   When I put them on, I was pleased and relieved to find the toebox pleasantly roomy and the shoe generally very comfortable.  As with the VF4%, the sensation of tipping forward feels strange, particularly when you’re not running, and the fact that the shoe doesn’t flex like a traditional shoe also takes a little getting used to.  Once in motion, however, everything felt surprisingly normal.

Derek: The upper is very thin and very breathable with very little structure. It works incredibly well in hot and humid conditions and reminds me of the upper seen in the Reebok Run Fast or the Nike Streak 6/Vaporfly v1. I imagine it’s the kind of upper that would shine on an ultra course like Badwater. Simple, but when made with the right foot volume in mind, gives an amazingly secure feel.

Sam: The upper is a very light, thin dense weave, very pliable, single layer, non stretch engineered mesh. Similar in materials, the mesh is thinner and considerably more pliable than the original Vapor Fly’s upper and clearly less dense and three dimensional than Nike’s Flyknit in the more recent Vapor Fly. 

The mesh is most similar to the Reebok Floatride Run Fast and Pro uppers although, unlike the Fast’s, it is unlined. It is an incredibly comfortable upper on the foot and I think perfectly suited to its ultra road mission.
The thinly padded tongue has a raised grid pattern below a non slip outer material with a thin soft, stretchy mesh backing on the foot.
There is a very thin, highly breathable stretch bootie, about 2 inches long connecting tongue to midsole. The tongue, lacing, and upper work quite well, despite their seeming lack of any structure holding the foot to the broad mid foot platform with the rear active foot frame midsole sidewalls certainly assisting.

This is one highly breathable, drainable, non water absorbing upper. I dumped lots of water on my head at Boston and never had that squishy shoe feel or any sense of a gain in shoe weight. Note the light coming through the unlined upper and even the stretch bootie in the photo above.
The heel and achilles collars is lightly and softly padded 
In this area we see the only “overlays”, actually stitched in threads connecting lace up to the heel.
The toe box has has a very thin, very pliable underlay at the toe bumper but otherwise is completely overlay or even inner mesh lining free. The front foothold is excellent and totally pressure free if roomy.

There is a very minimal heel counter but there is one. It is vertical at the rear, about an inch wide, and stiff for the first inch or so then with a softer stiffener above.
The rear clearly uses Hoka’s active foot frame for hold and stability as the midsole rises around the rear with the foot sitting down in the shoe. My only suggestion for improvement might be a slightly more cupped sock liner or a bit more extended heel counter to provide a bit more side support the heel.

Peter: Sam’s got all the facts covered up above. I’ll just say that the upper works beautifully (once the heel is dialed in). I might like the tongue to be just a hair longer, but it stays in place nicely due to the bootie.

Mac: The upper certainly minimal, but with a great gusseted tongue just the right amount of stretch to hold everything in place. Think: simplicity, weight savings, and secure. I too had to stop mid-run to tighten the laces, but once I did, it was go-time. Oh, and I had to switch out the white laces for blue ones:

Jeff: This shoe is going to get a lot of wear this summer on my routes in Arizona  if only because the upper is so breathable. Super thin, and the exact opposite of obtrusive, it was pretty easy to get a good locked in feel. Or so I thought, until my third run in the Carbon X, which was twelve hill repeats. After the first two I had to tinker with the laces to really clamp the shoe down, but once I did it fit perfectly. No rubbing, no hotspots, no heel slip, nothing. The tongue is definitely thin, and if you do have to crank down the laces to firm it up you might feel a little pressure on the top of your foot, but nothing resembling pain in any way.

Michael: Even though I’m on “Team Knit” when it comes to uppers, I was quite satisfied with Hoka’s offering here. No hot spots, no heel slippage, and no odd sizing quirks as far as I was concerned. The material is stretchy yet breathable, and provided more than ample lockdown on some technical hardpack trails with tight turns. I would have liked to see tongue sewn down on one side, as that tends to alleviate issues mid-race, but that’s the pickiest of nitpicks.

Hope: I think I would’ve been happier with a somewhat snugger upper, but I get why it was designed this way and I do appreciate the thought behind it that Sam described above. For me, the laces only helped me to achieve side-to-side lockdown, not up-and-down lockdown. So it felt like every time I picked my foot up off the ground that the Carbon X was a half beat behind it rather than completely in sync. Generally “slipper-like” is not the feel I’m going for in a racer; I’d rather feel more locked down and secure. That said, heel hold was adequate and the upper felt blissfully light.

Dom:  The upper was a great and happy surprise to me.  As the others have observed the fabric is very lightweight, airy, and with little stretch.  I was expecting it to feel narrow and constrictive, but it proved very comfortable.  Yes, foot retention is not stellar, but the upper is remarkably light, and supremely optimized for running fast in a straight line for a very long time.  For this usage scenario, I felt the upper knocked it out of the park.  For a couple of runs, I took the shoe onto the trails, which didn’t work out very well, but not because of any limitations to the upper. With the thin fabric, tremendous breathability, and white color, this should be a great hot-weather shoe: I’m guessing we’ll see a lot of these at Badwater!

Midsole and Outsole

Derek: The midsole/outsole combination plus the carbon plate give a nice rockered feel to the shoe that makes you want to roll forward in the shoe when you are just standing still. Overall the shoe has a fairly nice albeit firmer springy feel to it. I’ll get into it more in the comparisons but it feels similar to the React cushioning in Nike’s Zoom Fly Flyknit. There is plenty of stack in the shoe and there is plenty of vibration dampening going on over a wide range of paces. I don’t run off road much but my first couple of runs have confirmed that this shoe has great grip on roads and that lends great confidence when cornering hard or bombing downhill even when the roads are wet. Durability looks good so far though I think it maybe a bit early to comment. I only have 40+ miles on my pair so far.

Sam: The midsole is Hoka’s new Profly X light compression molded EVA. 66% of the overall stack is above the carbon plate. The carbon fiber plate is located just above the change from white outsole to blue midsole and sits approximately 15mm above the ground at the heel and at 10mm towards the front.  It curves up under the lateral toes to prevent re-supination

The plate location is lower at the heel and higher at forefoot than in the Vapor Fly where the plate curves down from heel to forefoot in a spoon shape. On the run, the X carbon fiber plate location results in both a softer heel and forefoot feel for the Carbon X and a flatter lower drop feeling ride when the 5mm drop vs.10 mm for Vapor Fly is also taken into account.

Hoka described the ProFly midsole as follows to us:
Carbon X uses more resilient foams  (than other Hoka’s such as Clifton). It has a strong compression set. This makes the feel very responsive and supportive, and should hold its shape better in the long term. Higher specific gravity means that it is not the lightest weight Hoka foam, and as a result it also doesn’t feel as soft/mushy. Rubberized foam (highly resilient) is used as the outsole with the carbon fiber plate changing how impact causes the foam layers to interact.

The full length carbon plate is located just above the thick rubberized foam outsole and is seen through the cavity just ahead of the heel.

Mid and forefoot strikers should be very pleased with the geometry as should moderate overpronators. Heel strikers, such as I am, need to focus on landing further forward with a slightly more pronounced forward lean or drive to keep off the heel in a similar fashion to how one runs the Vaporfly but here slower back on the heels paces are more easily accommodated than in the Vaporfly.

Sam: The outsole is an injected rubberized foam which varies in thickness and which I measure as approximately 15mm at the heel  thinning to to 10mm up front just behind the final toe off outsole which is somewhat thinner yet.
The wear of the outsole has been remarkable. It is barely scuffed in high wear places, with no visible loss of thickness beyond the dot pattern after 70 miles of fast pace running.

Note that the center areas above had no outsole pattern. I do wonder if the completely unworn rear bevel area is overly long and adds to weight and if its mass far to the rear contributes to slowing transition off the heel. Grip is excellent in large part due to the massive on the ground full contact. The platform is wide and stable front to back.
Heel landings, say on steep downhills, are remarkably well cushioned yet stable with no bottoming out. I do wonder is there is to much mass off the rear for the flats though. Note absolutely no wear at the rear of the bevel. Could it be moved further forward to help transition better off the heel?

The contrast with the Vapor Fly’s heel is striking, and while I am fine on smoother level roads in them, on steep downhills or uneven pavement the Vapor Fly is nowhere near as stable.
And seen from the bottom one can clearly see a wider heel landing, more filled in mid foot and somewhat wider forefoot footprint of the X. The pluses of the Carbon X geometry are considerably better stability and support but there is more weight, it is slower to come off the heel, as Jeff's says below sort of back weighted and has a somewhat less dynamic overall ride and toe off propulsive sensation.

Peter: Once again, Sam has the deets up there. I’ll say this: The durability and grip of the outsole have been WAY better than I could have hoped for. I’m somewhere near 60 miles with no visible wear and was out on wet roads this morning and it was as grippy as any other shoe I own. Pretty special.
Mac: The midsole/outsole is great. I freely admit that I was terribly disappointed when I learned that the midsole is “only EVA”, but whether it is the type of EVA or the shape of the carbon plate, this thing really encourages you to go forward. I get the distinct sensation that every time my foot hits the ground, it is being sprung forward upon toe-off. There is only one other shoe on the market that I can say that about. So, although I question the compression resistance of the EVA midsole, there is no doubt that this shoe does what they say it does.

Jeff: The midsole/outsole combination works well. As I mentioned earlier the shoe’s shape is friendly enough that virtually all foot types will be able to give it a shot, and that’s nice. There is plenty of cushioning at every stage, though I have noticed an interesting quirk with the Carbon X. During every run it felt just fine for the first five miles, and after that it felt amazing. It isn’t that the shoe felt dead during the opening five, just that it felt like almost everything else. 
Nicely cushioned, not all that responsive, smooth transition, but then after five miles it felt like it had a little extra pep. I could feel the rocker/plate when standing still, it really wants you to move forward, and that feeling showed back up right around the five mile mark. Sadly, I’ve yet to be able to take them on a true long run of 15+ miles, but I have one on the schedule next weekend, and if it doesn’t go as smoothly as I assume it will, I’ll update it here. 

Sam nailed it though, the extra width gives a level of stability not found in many other shoes with this much stack in combination with light weight, and the outsole, despite being some form of EVA, will take plenty of beatings. The white outsole is plenty dirty (I blame living so close to the native desert and the streets having a constant dirt blanket blown over it) but not worn down at all. 

Worth considering, the carbon plate makes it very stiff, and that takes just a bit of getting used to. Each run resulted in an unusual foot soreness after the fact, likely a result of the ultra stiff carbon fiber reinforced midsole. There is not any twist or flex to speak of, and it’s not a shoe breaking glitch, it definitely can beat up your feet a little more than most Hokas will. 
My more minimal gripe deals with the junk in the trunk. The Carbon X back end reminds me of virtually any version of Porsche 911, and probably not for the reason you think. Being one of the only true rear engine cars (it’s not mid-engine like so many others, Porsche’s mainstay puts the motor’s center of gravity on the back side of the rear axle) there’s a lot of weight hanging off of the back, and the Carbon X had the same feeling for me. I could feel the extra midsole/outsole stacked up behind my heel. Not a huge issue, but something worth noting.

Michael: But for recovery days, I’m all in. The midsole is responsive, and every bit as “springy” as you’d hope of a shoe with “carbon” in the name. Like Mac, I was anticipating some sort of technological smorgasbord with all of the pop and circumstance surrounding the X, and learning it was “only” EVA did feel hollow. But, again like Mac, I was unduly impressed by the bounce you get in this racer. Yes, the midsole is stiff (more on that below), but it’s a terrific compilation of materials that really do make you want to up and go on the trail.

Hope: My impression is basically like Michael’s. After that first adrenaline and hype fueled run, I stepped back to really see how the shoe felt over approximately 30 miles. It’s okay, but not amazing for my biomechanics. It’s an amazing feeling to slip on the same model that champions just used to set a new world record. It didn’t make me run like them. The rocker is fairly propulsive, but the plate isn’t all that noticeable. There’s no pop. Encasing the carbon fiber in regular EVA deadens a lot of the wow factor. I have had blister problems recently with the Hoka bucket seat design in the much softer Clifton 6, but happily didn’t suffer similar issues in the Carbon X — my feet don’t sink down as much into this firmer midsole.

Dom:  I don’t have much to say about the midsole specifically.  To my mind, the amount of squishiness is right on the money.  It’s definitely not as responsive as, say, a Nike VF4%, but the extra sponginess makes the Carbon X feel more forgiving and gentler on the body when racking up high miles.


Derek: Let’s face it. Nike changed the landscape of what’s possible in terms of mechanically augmenting the ride of a shoe when the Zoom Fly first released, nevermind the Vaporfly. It’s been 2 years since the Zoom Fly first released, and to-date the Carbon X is the only shoe that comes close to equalling the ride of the Zoom Fly, and then some.

I don’t know if it’s deliberate, but the Carbon X has design elements that address a lot of the complaints (some) people have about the Zoom Fly. The Carbon X feels very versatile to me, and I had no issues going anywhere from 8:00/mile to 5:40/mile pace and everything in between, though I have to say the shoes make you want to pick up the pace. So much so that my first two runs ended up going at 7:10-7:15/mile pace when they were meant to be easy runs. The ride quality sits somewhere between the Lunarlon Zoom Fly v1 and the React Zoom Fly Flyknit, veering closer to the feel of React than Lunarlon. For long runs, and full disclosure I’ve only done one long-ish run in it so far, the shoe does seem to fight off fatigue better than any other trainers I’ve tried in this weight class. I like how the wider footprint of the shoe makes it incredibly stable around corners. Initially it was almost too stable and transition (from supinate landing to pronation) felt a bit awkward for the first 20-30  minutes in the shoe, but by the end of the first run I felt like the foam had broken in and the transition from supinate landing to probation had smoothed out considerably. If there’s a flaw in the shoe, for me it may actually be that the carbon plate is not rigid enough. I don’t know if it’s the stiffness of the plate or maybe the way it’s curved up that’s responsible for this but I suspect maybe the former.
When I’m rolling through the stride, I can just about feel the stiffness of the shoe give just at the metatarsophalangeal joints, and in order to preserve the rocker effect, the shoe must hold stiffness all the way through the toes. I know the others have commented on how stiff the shoe is, but as someone who trains a lot in stiff shoes (the Zoom Fly took up a lot of my training miles over the last 2 years) I feel that I know how to roll with the stiffness of the shoe rather than try to fight it and toe off like I would in a regular trainer. With a stiff shoe, you want to let the rocker swing your foot through the stride and power off through your glutes and hamstrings rather than try to get any extra oomph from balls of your feet (with your calves). With the Carbon X I can feel my toes flexing just before the shoe leaves the ground, and I‘d rather it didn’t (in this sort of racer). It’s like the plate stops helping at the very end of the stride. Still, this is small print stuff and a minor gripe on a otherwise outstanding shoe for me. 

I know I keep harping in about this, but if you take a Zoom Fly (mesh or knit), take away the overly rigid or insufficiently supportive heel count, take away the unstable narrow platform, take away the poor wet weather grip, and voila you get the Carbon X. Not everyone has issues with the Zoom Fly. I know plenty of people who love it, but for the few who have fit or stability issues with it, the Carbon X is the ultimate solution.

Sam: First, no one will ever complain the Carbon X doesn’t have enough cushion for heavy mileage at pretty much any training pace. There is tons of well controlled softer cushion here with a fantastic mellow sinking, bounce and some spring. I say bounce and spring as the foot clearly sinks into the soft foam, meeting first the stiff plate and then the rubberized foam to provide a pleasant feeling with a muted (by the stack above and thick outsole)  yet quite decisive energy “return”.
The 5mm drop is not flat feeling (as in the 1mm carbon plated Carbon Rocket) or with a pronounced sense of heel height then plunging to the toe (Vapor Fly). I did feel that the midsole/outsole foam softness in such a thick stack, or maybe the weight and width of the rear beveled area, or possibly the near the ground location of the plate, or the wide midfoot platform geometry or some combination had me lingering on the heel longer than I would like in a half marathon type racing shoe. More midfoot to forefoot strikers will likely not notice this. This said, the ride was sublime for all forms of long run training, soft enough, energetic, stable with a super well cushioned yet dynamic springy feel.

The forefoot is soft and incredibly plushly cushioned but also stable with muted snap from the full carbon plate. While I never had  tired or sore feet on any run, I found the forefoot a bit soft and plush for my tastes as when the pace picked up to my half pace of around 7:30-7:40/ mile pace things were not as snappy as I would like with the feeling  of a more soft very stable bounce than quick response.

One can sense the snap provided by the plate but due to the cushioning above and below there is never also a sense of abruptness or firmness in its interaction with the rest of midsole and outsole.

There is also not as pronounced a forward sinking sensation as in the Vapor Fly where one sinks all the way down to its plate and then to a sharp toe off. There is clearly a more cushioned forefoot feel here when compared to the current Vapor Fly, with testing of the %Next with additional forefoot foam to come. There is a sense of a forward compression of the midsole then spring from the plate and rebound from the rubberized foam outsole.

Despite the stiffness of the shoe, there is not the usual Hoka need to use a very pronounced knee drive to move off the rocker. This said the ideal paces for the shoe for me were tempo to marathon pace,  as while stable and dynamic at those paces the softness starts to catch up with the need to toe off fast and decisively as the pace quickens.

Peter: For me the ride is a little confusing. I’ll say this though; the shoe started to open up for me on my third run. The stiffness was kind of preventing me from pushing through my stride on first couple of runs and I wasn’t sure how much I liked the ride. Since that run, the shoe has opened up and felt terrific. I like it at moderate and slow paces, but I find it difficult to get any faster than marathon pace in them. The ride is less soft than the Rincon and rides an interesting line between cushioned and firm. I would have said it felt overly firm--kind of punishing on first run, but as I’ve run more it’s gotten to feel more like an extension of my foot.

Mac: I will say that the ride is a tad soft for my taste. Yes, the carbon plate helps with the responsiveness tremendously, but there is still just a tad of that “Hoka Marshmallow” feel. That said, it is much more responsive than other Hokas I have tried, and also more responsive than Everun or Boost. I will also say that in a varied paced workout I did: 15 Tempo, 5x1k CVs, and 5x200 fast, I hit my splits fine even though I went into the workout with my legs completely dead from weekend runs. So, it is still early, but I definitely get the impression that these will help the runner keep the pace up even when the energy starts to dwindle.

Jeff: My pair of Carbon X showed up the day before I was attempting a 5K PR, and I seriously considered racing in it. I wore them for my warmup miles, but the shoe didn’t scream 5K racer to me, so I changed shoes for the race. I think that was the right move, but for a race of any longer length, I think the Carbon X could be the shoe. I would agree with Mac, it is remarkably more responsive than Everrun or Boost, but I didn’t think it was overly cushioned. On a few of the runs I could have gone for a little more squish and a little less carbon plate, but ultimately I found it to be a great shoe to run almost any pace slower than 5K. Also, this might be the best downhill shoe I’ve ever worn. Not sure if it’s the different angles at play or just how well locked down the upper is so there’s no slipping or sliding inside the shoe, but the Carbon X flew up the hills and glided down them - and that’s not the case for all shoes.

Michael: As I noted when I first slipped on the Carbon X, this is not a soft shoe. It’s cushioned, undoubtedly, and it’s comfortable, but it feels like a racing flat - almost like a springboard under your feet. Nike’s Vaporfly has midsole foam that is undoubtedly squishy to compromise the rigidity of the carbon - not so here. And that’s more than fine by me - just don’t expect to break out the Carbon X for your next recovery run. The Carbon X is a shoe best served fast, and when you’re turning over and activating all of the technology in the midsole, it is an absolute joy to run in.

Hope: I think my experience most closely follows Peter’s.  I struggled mightily in the Carbon X with a 6 x 5:00 @ threshold pace workout. I liked the firmness and the smooth roll forwards, but I just felt like I couldn’t get going fast at all. Weirdly, the ride feels smooth while the midsole feels distinctly stiff. It’s a lot of foam already then it’s reinforced by a carbon fiber plate, so this should be no surprise I guess.

Dom: When stationary, the shoe feels weirdly stiff and tippy, but once in motion, the carbon plate is surprisingly unobtrusive.  In a way, the spongy foam and carbon plate cancel each other out, so the shoe doesn’t feel taut and unforgiving like traditional racing shoe, but also doesn’t feel energy-sapping squishy.   It is a matter of opinion whether you feel this is the best of both worlds, or fails to fully satisfy either.   I liked it a lot.  At faster paces I felt like I was flying.   So subjectively, at least, the shoe feels efficient.  I would need to race or do a lot of treadmill testing in the shoe to figure out whether or not this perception is real.

I’ve run a lot of races in Hokas, often using their road shoes (Clayton 2, Mach 1) on trail, so I’m used to taking their shoes where they’re not designed to go.  Alas, the Carbon X is definitely not trail appropriate.  When I took them off-road I found that as one might expect, the slick sole is terrifying in mud, allows the grit to behave like ball-bearings on dry, loose surfaces, and the carbon plate has strange and unexpected dynamics when cornering hard.  This shoe is excellent at going in a straight line, but doesn’t like to change direction too rapidly.   In this respect it is noticeably superior to the Nike Vaporfly 4%, but that’s not saying too much.

Conclusions & Recommendations
Derek: Just based off the weight of the shoe (which is not entirely fair since I set my marathon PB of 2:41 in the Zoom Fly v1 of the exact same weight), I am judging this shoe as an uptempo trainer and ultra distance racer. In that respect the closest competitors are the Nike Zoom Fly, Adidas Boston Boost, Saucony Zealot, Brooks Launch etc.
In that respect, the ride is outstanding over a fairly wide range of paces, and the shoe provides very very good cushioning for its weight. When you couple that with a fit profile that will accommodate a lot of foot shapes than eg Zoom Fly and Boston Boost, you have a big winner on your hands. The downside is the price. The Carbon X comes in at $180 which is $20 more than the closest competitor in the Zoom Fly Flyknit, and that’s not even taking into account many of the Flyknits will discounted soon as the ZF3 looks to be releasing in the near future. Still, fit plays a very big part in whether a shoe works, and I suspect many people who find the ZF unstable or don’t fit well, or simply don’t like running in a high drop shoe, will love the Carbon X.
Derek’s Score: 9.2/10

Sam: The Carbon X was created for elite Ultra road racing. It provides a unique blend of soft, bouncy, very plentiful cushion, stability and carbon powered propulsion. It has proven a very fine longer than half racer but its real strength for me is as a heavy mileage, anything but the fastest tempo paces, lightweight trainer. They were the ideal shoe to race my 20 mile Boston tune up in and did fine at Boston as well, even if I didn't. Recovery runs, daily mileage, long runs at most all paces are gobbled up with ease by the X. As a mostly heel striker, soft high heel stack and 5mm drop tend to start to have me lingering at the heel at faster paces and the forefoot could be a touch firmer. I do wish for a touch more drop overall or slightly firmer midsole foam.

Carbon X has a very comfortable, minimal, pliable, thin, single layer upper. It does not have the usual race snug shoe upper. It is airy and roomy yet is decently supportive. This upper is ideal for summer heat and long run foot swelling as well as wet conditions as I found almost no water is absorbed and drainage is excellent. I have never had any blisters, arch bite, pressure or irritation of any kind beyond a touch of lace bite using thinner socks in my half size up from normal pair.

The fit is quite voluminous. High volume feet should be very happy in this upper. Note the height and room when stuffed with paper in the photo above. Not to worry the upper wraps the foot very well if you don’t have a low low volume foot, but again with a more "comfort "as opposed to snug performance fit, as intended for its road ultra use. While the production sock liner does improve the heel hold it could be improved with a more cupped sockliner or more heel counter itself. Very low volume feet may struggle to fit and may need to consider sizing down a half size or using slightly thicker socks.  There are no overlays and stiffening way up front to get in the way of toes which will assist in fit.

The smile and comfort factor is huge with this shoe. It is one of the finest, most fun and most comfortable, top to bottom. trainers of recent years, if not ever, for me. Very decently light for their maximal stack at around 8.8 oz , soft and easy running, they shine at slow to tempo paces for me, so as intended ultra paces. The outsole durability has been outstanding to date indicating a long long run life for the X.  And, as they firm up over time I suspect their shorter racing performance will improve. If you are seeking the ultimate in light weight super cushion and comfort, with the snap and stabilizing influence of carbon in the mix, the Carbon X is a great new option.
Sam’s Score 9.80/10
My deductions are for “shorter” racing distance performance and fast pace use. I deduct for heel and forefoot softness and muted or delayed responsiveness at marathon to half and faster paces, they are just a bit to forgiving, and for weight. A bit less stack overall, a closer to the foot carbon plate at the heel, more drop, or a slightly firmer or non EVA more energy returning foam in the mix (but not as firm as Carbon Rocket’s) or a combination would move the X into Vapor Fly racing territory.

Mac’s Score: 8.7/10 (Personal Top 5; my scores are generally lower than those of my peers.)

Ride: 9 - Very good toe off and cushion, just a little soft for my taste, plus it is on the heavy end for a  premium racing shoe. Fit: 9 - Just a little loose in the heel and you have to cinch it down to get the secure fit you’d want for running fast, but plenty of toe box room and great, simple tongue and upper. Value: 8 - It does what they say it does, but a $180 price tag and only average expected durability will knock it down a peg. Style: 8 - Purely subjective here. It is honestly a really great looking shoe, but the laces look cheap.

Jeff’s Score: 9.4/10 (I too subscribe to Mac’s scoring rubric, so while my score might be lower than the others, I’ve been raving about this shoe to anyone who will listen). Ride: 10 - it runs super smooth when settling in to a cruising mid to upper 9 minute pace, and has a little pop or snap to it when pushing close to a 7 minute pace. One of the most fun running shoes out there. Fit: 10 - the best example of less is more I’ve experienced. Value: 8 - It’s a blast to run and I get the impression it will last a long time, but $180 is still $180. Unless it lasts fifty percent longer than lots of other trainers, it is a pricey proposition. Style: 8 - the laces feel cheap, and there’s way too much white for a shoe that’s ostensibly getting loads of miles piled onto it. Last thought - if this is what the Nike Pegasus Turbo turned out to be, it wouldn’t have been a controversial shoe at all. This is what it should have been, and I’m just glad somebody made it.
Michael’s Score: 9.8 /10 . The hype here is real, and I think we (finally!) have a legitimate Vaporfly competitor. For its intended use cases - longer races and serious training efforts - the Carbon X is a terrific option. The only negative I have is the weight, but even that is hard to discount too severely, considering the versatility of the shoe. When the Vaporfly was released, there was some skepticism at racing in a flat 2 ounces heavier than Nike’s other offerings - skepticism that was quickly squashed. I think the same will play out here. The Carbon X carries a few more ounces than the competition, but puts them to good use. This is largely what I think we all expected of the Carbon Rocket (a fair shoe in its own right), and I’m glad I got to test it. Bravo to Hoka on such a strong offering.

Hope’s Score: 9.4/10. 
-.1 for laces that didn’t stay tied in a double knot
-.1 for price
-.2 for overly roomy upper
-.2 for stiffness
I’m not throwing out my pair of the Nike VaporFly 4% Flyknit yet, but this is an interesting shoe. I have yet to test it over long distance, so I hesitate to make a final recommendation. Many of the design components are in place for this to be a great long haul racer, but for me they haven’t yet added up to a shoe that feels particularly fast or even particularly special. As has been said, the high-volume upper might pose a challenge for some (as it does for me), but the roominess should accommodate the foot swelling that can happen late in an ultra. If you have $180 to play with and want to see what all of the fuss is about, I think it’s worth a try, but I won’t go so far as to say that this is a “can’t miss” shoe.

Peter’s Score: 9.2/10 
-.3 for upper feeling a bit baggy/hard to lock down--which robs the shoe of some synergy between upper and mid/outsole
-.3 for weight. If you’re thinking of this as a racer, the weight is problematic. If thinking of it as a lightweight trainer it’s no problem.
-.2 for price. Not cheap!
I’m writing this before reading anyone else’s conclusions. Though I’m tempted. I’m a big fan of this shoe--but not necessarily for the things I would have thought. Over a few runs this shoe has broken in really nicely and is for sure a shoe I reach for (and traveled with this week). The Project X is a great day-to-day trainer for me. I’m happy to take it out for long runs or just daily runs and would have no problem putting some tempo miles into it. It is not, however, likely to be a race shoe for me. I just can’t seem to get up to really fast turnover in them. Between that and the heavy price tag it’s hard to give the Project X a full 10/10. I am thrilled with the durability and grip of the outsole and I can see putting TONS of miles in these--and yes the breathability is terrific for a summer shoe.

Dom’s score: 9/10.  Generally running shoes are optimized for efficiency (race shoe) or comfort/forgiveness (trainer).  Have Hoka managed to thread the needle and create a shoe that does both well?   Subjectively, yes.  I felt fast and comfortable in the Carbon X.  But I find it hard to give it a stellar score without knowing quantitatively whether or not I run faster in it than a conventional shoe lacking the carbon plate.  I wasn’t able to do a series of matched runs in different shoes at the same intensity.   The shoe is a little heavy compared to race shoes (50 g per shoe heavier than VF4%) but lighter than most max-cushion shoes.  Otherwise, there’s a lot to like.

Jamie Hershfang’s Review
Jamie participated in Project Carbon X races and was on the unofficial world record setting 10 x 10K team and shares her race report here.
My initial impressions of the shoe were mixed. We had the opportunity to run in the shoes the day before the race and get a feel for them. I ran an easy hour, finishing up with some quick strides. Putting the shoe on, it definitely felt spacious enough for my wider toe box. As someone who casually wears the Cavu walking around, it definitely felt accommodating. I typically wear a size 8 in running shoes, and found a half size down in HOKA works well, so a 7.5 fit perfectly. Over the past year, I’ve raced in the original Vaporfly 4% as well as the flyknit version. I would definitely compare the fit of the Carbon X to the original Vaporfly. The upper mesh was very breathable but felt secure around the heel and ankle.

In terms of running in it, my initial thoughts were that it felt just like a lightweight trainer. After an easy hour of running, it wasn’t until I did some quick strides that I could feel the responsiveness of the shoe. It felt springy off the toebox, and felt like I could turnover well. For those who heel strike, they may find the shoes feeling flat and firm. For the mid to forefoot strikers, they may definitely find a love for the Carbon X.

I continued training in the shoe after I got home from California. I used them for a long run, some 200s, and a tempo workout. I felt like they felt best for the 200s, when I was able to roll off the top of the shoe and feel the effects of the Carbon plate. They felt rather flat over the course of a 20 mile long run, and a little bit too much shoe for my liking for a tempo workout. I believe this is due to the differences in my form over the longer distances and when running fast. I will probably continue to use them as a lightweight trainer, but still prefer the Vaporfly 4% for my racing shoe.

Vapor Fly 4%
Original July 2017 Ice Blue (RTR Review)
Derek: not a fair comparison simply because the weight difference is quite significant. The VF is just a springier more exciting ride.VF also feels stiffer through the forefoot. Having said that, the Carbon X beats it hands down in terms of outsole grip and stability. I would also pick the Carbon X for longer races where I feel like I may want that extra stability for when I slow down.

Sam: I found the very first 2017 Vapor Fly was softer and bouncier than subsequent versions such as the Obsidian color and is the closest in cushion feel to the Carbon X. Its roomy, if somewhat thicker upper, is similar in fit to the Carbon X with slightly better heel and midfoot hold. The Vapor Fly’s narrower midfoot platform and broad upper made it feel like the foot was collapsing to toe off and that was a great feature to drive down and forward to take advantage of the plate.  I do miss the 10mm drop of the VF in the Carbon X at faster paces, where along with the plate closer to the heel, the drop helped drive the foot forward and down to  toe off.  The OG VF was truly outstanding for racing marathons all the way down to 5K for me, but I would pick the Carbon X for a hilly course such as Boston due to its stability on the hills or rough pavement if you tend to end up back on the heels when tired.. This said, while some train in Vapor Fly they don’t hold a candle to the Carbon X when slower paces, for me 8:30 to 9:20 minute miles and slower are in the training mix as the Vapor Fly's heel landing is narrow and unstable in comparison. While not the ultimate racer, as the VF has proven to be for many, the Carbon X is for me the ultimate, super cushioned performance trainer.

Hope: Sam basically has it covered here. The Carbon X has an even roomier upper than the already roomy OG VaporFly 4%, but its heel is far more stable. The OG VaporFly 4% is fast for me at any distance, so I prefer it.

Dom:  I bought into the hype of the original VF4%, and bought a pair (at extortionate cost) for my occasional detour away from the trails to run a road marathon.  Quibbling about the comfort of the VF4% seems almost irrelevant since the shoe is unambiguously built for efficiency above all else.  That said, the Carbon X is definitely more comfortable.  And it goes round corners much better than the VF4%, which is downright hazardous when not going in a straight line.  But if I were to run a road race tomorrow, I would still pick the VF4%.  Up to 50 miles or so, at least. For longer distances, or for training runs, I would opt for the more comfortable, more forgiving Carbon X.

Nike Vaporfly 4% Flyknit (RTR Review)
Derek: it’s a very close contest here for me. I prefer the ride of the the Zoom Fly Flyknit, but the upper doesn’t work as well for me as the Carbon X’s. As an overall compromise, I would favor the Carbon X for the superior fit and lockdown. But it’s very close. The Zoom Fly is bouncier, but less stable, and doesn’t work as well for slower paces.

Sam: The Flyknit upper is effective but has a far more performance oriented snug fit than Carbon X. Not a shoe I would train in, or be happy in with swelling feet in summer heat as I would be in the Carbon X. Considerably firmer than the original Vapor Fly, the newer Vapor Fly, while still magical, it is far less comfortable or easy to push fast than the original for me.

Hope: I like Flyknit VaporFly 4% far better than the original for its more secure fit. The stretchy FlyKnit is super, super comfortable to me even over 26.2. I’d happily take the VaporFly 4% FlyKnit over the Carbon X, at least at this point.

Peter: Against all vaporflys I say this: The Vaporfly makes me feel fast, and I find it hard  to run slow in them. The Carbon X is fun, but I find it harder to run fast in them. For speed it’s the Vaporfly all day. For any sort of stability and especially on cambered roads I’d go X.

Vaporfly 4% Obsidian
Jeff: I didn’t get a chance to run in the first few colorways of the OG VF4%, and I’ve heard that the obsidian version I have feels a little firmer underneath the foot than earlier versions. All I know is compared to the Carbon X, the VF feels pillowy and almost fragile it is so light. It also has an incredibly narrow midfoot that makes stable runners feel unstable, and while the Carbon X is expensive at $180, adding an extra $70 just seems insane. For racing it is hard to say you shouldn’t go VF’s if your wallet can stomach the hit, but for a regular trainer, there’s no question, Carbon X.
Michael: I liked the Obsidian-colored Vaporfly (used it in my 2:31 marathon PR, at least) but, even with my “regular” width feet, had some problems with hotspots and tightness on longer efforts. The slightly roomier design and wider platform of the Carbon X should alleviate some of that - but at what cost? Stepping away from the VF is a “risk” (given all its purported to do), and for those who fit well into the Vaporfly would be wise to stick with it over the marathon distance. The sizing here (absent the wider platform of the Hoka) was about the size - I was comfortably an 8.5 in each.

Nike Vapor Fly %Next 
Sam: I haven’t yet tried the %Next but suspect with its increased forefoot cushion stack and 2mm lower drop at 8mm it will feel closer to Carbon X than prior Vapor Fly upfront. It’s Vaporweave upper echoes the thin upper of the Carbon X but it is unclear to me as of yet how pliable it is. Clearly it weighs considerably less and it also seems likely it will be less stable at the rear than Carbon X.

Hoka One One Carbon Rocket (RTR Review)
Sam: The Carbon Rocket is Hoka’s elite road racing and marathon shoe with carbon fiber plate above a rubberized outsole so a very similar construction. It feels considerably firmer than Carbon X and its 1mm drop combined with carbon fiber plate sure is far more noticed than in X's at 5mm drop with softer cushioning, yet I find it also incredibly well cushioned and easy on the legs. It weighs almost an ounce and a half less than the  X.  It is on a narrower platform with a firmer dual density midsole with an overall lower stack which is 26mm at the heel, 25mm at the forefoot, so 6 mm lower at the heel and 1mm lower up front. It has a somewhat thinner 8mm rubberized foam outsole with some rubber patches. I would turn to it for racing a half and below before the Carbon X.

I found the Carbon X heel height feel to be only slightly higher than the Rocket’s at faster paces, likely due to the Rocket’s firmer midsole and patches of heel rubber. Some of our testers found it “flat” feeling and firm. I personally did find it different but a very fast and very easy on the legs shoe and ran distances up to 15 miles in them. Its very thin upper is clearly a more speed performance oriented fit while in no way being uncomfortable. I prefer Rocket’s upper for racing and X’s for training  It comes down to preferences. If you like a softer bouncy more training focused ride the Carbon X, if you prefer a firmer highly responsive ride if low drop Carbon Rocket
Mac: I know the Rocket (7.5 by my score) is lighter and a little firmer, but the Project X, for me, is superior in every other measurable way. Cushion is more protective, and even though the feel is a little soft for my taste, the toe off is much more dynamic than the Rocket’s. Project X by an Ultra for me.
Hope: The Carbon Rocket was way, way too stiff for me. I desperately needed more rocker from that shoe. Carbon X all day for its more forgiving ride.
Michael: I was (and still am) a fan of the Carbon Rocket, but the Carbon X is a better choice at nearly every distance. Surprisingly, where the Rocket may have the edge is (despite its name) slower days, or longer efforts where the relative flexibility may be appreciated. Even so, the Carbon X is faully competent racer or trainer. Moreover, the X has considerably better fit (especially heel lockdown) and feels slightly less sloppy in the forefoot (though the upper on the Carbon Rocket is still quite impressive)
All told, for nearly all workouts (and about any race I can think of, 5K and up), I’m taking the X.

Hoka One One Rincon (RTR review)
Sam: The Rincon is considerably lighter at 7.1 oz. It is somewhat firmer and not as springy as it has no carbon fiber plate. It actually flexes, a first for me in a Hoka whereas X is entirely stiff and rocker based. If you like a very well cushioned ride in a shorter race capable shoe for faster training paces in a Hoka Rincon makes a good pairing with X, with X the big mileage and slower days shoe.
Jeff: Sam summed these two up well, they definitely pair well together, though I found the Rincon was also great for longer days, and I thought it felt much better when approaching all out speed. As much as I like the Carbon X, I have a hard time rationalizing why you should spend an extra $65 on it. The Porsche metaphor from earlier comes full circle here - the Carbon X is the 911 while the lighter and cheaper Rincon is the Cayman, and lots of car publications say the mid-engine Cayman is ultimately the more fun option. Save the money, go Rincon.
Peter: The Rincon feel softer to me. Am I on crack? They are different feeling shoes, I really like both of them. I too feel like I can get going faster in Rincon than the Project X, but over long distances I’d probably go Project X.

Hoka One One Evo Rehi (RTR Review)
MIchael: The Rehi is one of my favorite flats of the last couple years, and with its water-resistant upper and drainable midsole, remains my go-to workout shoe on any wet day. Both shoes run about the same, size-wise; they’re cut like racing flats (low-volume Rehi, especially) so those on the border should consider a half-size up if they want a more trainer-like fit. Overall, I’d take the Rehi for a 5000-10,000m race on the roads (or anything on the track); anything longer and it’s the Carbon X.

Skechers Performance Ultra Road 3 and Max Road 4 Hyper (review soon)
Sam: Both Skechers Ultra shoes share a similar maximally cushioned softer ride with the Carbon X but have no carbon fiber plate. I have wear tested the Max Road Hyper and it is the shoe I might put closest to the Carbon X. While it does not have a carbon fiber plate for a distinctive if soft dynamic pop off the forefoot or quite the downhill and overall stability of the X, its Hyper Burst foam midsole is plenty stable, very well cushioned with a more springy lively feel inherent to the foam itself with the midsole a single layer with a more conventional outsole. I think most will find the Max Road 4 easier on the legs with an overall smoother ride feel but with less dynamic pop than X.

Skechers GOrun 7 Hyper  (RTR Review)
Mac: The SGR7H (8.0 by my score)  is the closest shoe I have to a highly cushioned daily trainer / long distance racer - even if there is less cushion in the SGR7H, the feel is similar. The Carbon X has a much better upper than the SGR7H - what shoe doesn’t? - but the shoes each have a similarly dynamic midsole. Carbon X for long stuff, but I will save the Hoka some wear and tear by training in the goRun 7. (That said, I expect the Carbon X to be a FANTASTIC mileage shoe; I just can’t get over the expectation that the lightweight EVA will compress quickly.)
Jeff: I’m with Mac here. The upper comparison doesn’t exist these two shoes are so far apart, but beneath the foot of both these shoes there are really great things happening. If your foot works in the GR7H upper, then you’ve won the genetic lottery and congratulations. For the rest of us, I’d say it is worth the extra money for the Carbon X.
Hope: I think the midsole of the GR7H feels more special, but its upper has practically no lockdown whatsoever. The Carbon X seems ready to soak up tons of miles, but I think the GR7H is more fun (and its fit can be dialed in with creative lacing), so it’d be my pick. Hard to compare shoes with such radically different tech and price points.
Peter: Yeah, what they said!

Altra Paradigm 4.0
Mac: The AP4 (7.4 by my score) is the only maximal shoe I have put any serious miles in. Although it is possible that the AP4’s Ego midsole may be more durable, the Carbon X is much lighter, more cushioned, much more pop on the stride, and the upper lockdown is MUCH better than the AP4’s. Carbon X, hands down.

Pegasus Turbo (RTR Review)
Sam: Also soft with similar heel cushioning feel, the Turbo is not nearly as stable front to back and has a soft kind of formless feel. Its awkward upper is not nearly as comfortable, especially upfront. Despite Zoom X foam in the Turbo which has more rebound feel,  the return is poorly “managed” as there is no plate in the mix and heel landing is narrow. Carbon X all day any day for me in the soft  faster trainer category.
Jeff: Completely spot on. I know that shoe development takes a lot more time, but the Carbon X feels like it could have been the result of Hoka engineers running in the Pegasus Turbo and saying “We can do this better.” And they did; much, much better. Carbon X by a country mile.
Hope: Although the Peg Turbo has grown on me somewhat, I’m with Sam and Jeff on this one. Hoka made the lightweight cushioned shoe that Nike was aiming for.
Michael: Substantially different feels here; while the X is about as stiff a shoe as I’ve tested, the Peg Turbo is comparatively as soft. It’s spring vs. marshmallow. For those seeking a more locked-down fit and race-ready option, the Carbon X is my choice. Those needing pure leg-recovery shoes and not looking for any spring-like action would be happy in the Pegasus Turbo.

New Balance Fresh Foam More (RTR Review)
Sam: The More is maximally cushioned but considerably firmer in feel. Also a very stiff shoe but without a plate so with far less propulisve spring, its geometry seems to lack an effective rocker in comparison to Carbon X. I would call it more responsive and firmer in feel but not nearly as much fun to run daily as the Carbon X. Its upper can be challenging for lower volume feet, more so than the Carbon X’s for me as it less pliable and foot forming and more voluminous.
Jeff: On paper two very similar shoes that are real world extremely different. I’m with Sam, go Carbon X even if you don’t have low volume feet. It runs much better at all paces.
Hope: The FFM was the faster shoe for me, but I think more people will do better in the Carbon X’s upper. I’d love to give the Carbon X’s plate more time to break in before making a final pick, but I think I’m reasonably comfortable picking it over the FFM.

Nike Zoom Fly Flyknit (RTR Review)
Jeff: This feels like the most obvious comparison. Nearly identical in weight, sporting a more traditional cushioning plus a carbon fiber plate, both shoes could be raced in for longer distances but ideal for training miles. I’d give a big advantage to the Carbon X for the upper, but the midsole comparison is more complicated. ZF FK isn’t as comfortable, but it does feel slightly better at faster paces, while the Carbon X feels substantially better during easier runs. The midsole/outsole shape could be part of that, the ZF FK is awkward during easy miles. As much as I like the ZF FK, definite preference to the Carbon X for being an all-around more usable shoe, and all-around more comfortable.

Skechers Performance Razor 3 Hyper (RTR Review)
Derek: The Hyperburst in the Razor 3 is noticeably softer and bouncier than the foam in the Carbon X, but it lacks the rocker effect of the carbon plate. For that reason, I find it easier to hold an uptempo effort in the Carbon X up to a point; the weight of the Carbon X starts to become noticeable once you try to get under 10k pace. For fast workouts, the Razor 3 has been my shoe of choice for the past few months and that hasn’t changed. Overall the Carbon X is the more versatile shoe, but I’d favor the Razor for the really fast stuff.
Jeff: Even though it doesn’t have any carbon fiber in it, the R3H feels like a faster shoe with more pop to it. The upper isn’t as good, with a more cramped front end, and while there is pretty great cushioning (Hyberburst is legit) I am not sure I’d take it out for a 20 mile training run, I think half marathon is around the limit of where I’d take the R3H. The Carbon X can fill a number of roles, if you are looking for an uptempo big mile trainer, no question, it’s the Carbon X. Shorter, faster speedwork or races and you’ll see the Razor excel.
Peter: I agree the Razor is fun, fast and lighter. For training days I might hang in the Carbon X, but for any speed work I’d take the Razor hands down.
Hope: the R3H was one of my top shoes of 2018. I love the upper and the midsole is freaky good. It has a much more dynamic feel than the Carbon X, so it’s my pick.

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Greg S said...

Glad hope pointed out the laces not staying. Drove me nutz as my double knots did not stay put.

The heel lock is very annoying... Its loose unless you tighten them down just right.

Need to try them on a 20 miler long run as I hope they are better than an old pair of vaporflys

Curiious how they work for long runs as a midfoot to heel striker?

Sam Winebaum said...

Hi Greg,
Thanks for commenting!
No issues for me with laces and my prototype pair seems to have the same laces as production. As I hope described at least for me as a mostly heel striker I think they favor a mid foot strike more than heel at faster paces.
Sam, Editor
Thanks for reading Road Trail Run! See our page with links 100’s of in depth shoe and gear reviews HERE. You can also follow RoadTrailRun on Facebook, Twitter, YouTube and Instagram where we publish interesting run related content more frequently as well as links to our latest reviews.
Shopping through links on articles help support RoadTrail Run and is much appreciated!

Bobcat said...

I thought the carbon plate is supposed to flex and return energy? Whats the point if the shoe is stiff and relies on the rocker geometry? For instance, I sometimes like trail shoes for road use since the rockplate can give a nice springy toe off. Salomon S/LAB Sonic 2 was great for that reason. Now Salomon removed the plate from the new RA lineup *shrugs shoulders*. Just wondering how the flex and springiness compares.

Sam Winebaum said...

Hi Bobcat,
Carbon fiber is inherently stiff. It does not flex at all and doesn't in any of the carbon plated shoes. The shape/geometry of the plates and where they are placed in the shoe is what creates the propulsive effect. For example in contrast to Carbon X the eventually releasing Skechers Elite has an H shaped plate up front so an effect closer to the Sonic 2 which I agree had nice snap to it. The Vapor Fly plate is "spoon shaped" curving down at mid foot from being not far under the heel to right above the outsole. Carbon X plate is "flat" in the shoe with a bit of curve up at the lateral fore foot they say to prevent re supination. So all kinds of different approaches all with pluses and minuses and different ideal uses.
Sam, Editor

abaynp said...

Hi Sam, thank you for the thoroughly review!!
I couldn't find neither Max3 nor Max4 at the market. Can't wait for MaxRoad 3 Ultra (UltraFlight/FlightGen), and MaxRoad 4 Hyper (HyperBurst) reviews, and the compare with old Ultra Road 2 (5Gen) in term of cushion and responsiveness.
Thankyou so much Sam, hope you as healthy and fit as always :)

geomaz said...

Hello Sam! What is the deferences on stiffness and responsiveness between the carbon X and the duo. Are they similar in speed (equal fast)? Thank you very much!

Sam Winebaum said...

Hi Geomaz,
Carbon X is stiffer for sure and more responsive in the forefoot than Duo may be a bit less at the heel. Carbon X is more stable due to its wide foot print on the ground and more secure upper. As far as which is faster would depend on the runner, and the distance. As distance increases I suspect Carbon would be faster.
Sam, Editor

Anonymous said...

How does the Carbon X compare to the NB 1080 v9? I'm looking at the shoe as a long run, easy run, recovery run type of shoe - not necessarily a shoe for racing or speed work. I'm somewhat interested in the shoe for tempo work although that would be the primary purpose. I'm a heel striker. I'm 6' / 150 lbs. For long runs, I'd be looking at around 8:00 pace. For easy/recovery runs, I'd be looking at paces around 8:30-9:15. Tempo runs would be in the 7:30 range - but that wouldn't be the primary purpose.


BQ Trail Runner said...

Fifty-nine year old, 180 pound forefoot striker here, and they just didn't work for me. Even with the low heel to toe drop, I couldn't get the heel out of the way at times and had difficulty getting any faster paces going. Also didn't help that my achilles and calves were pretty beat to death after two runs in them. Seems to be an acquired taste, or at least some adapting required, and that's risky business at my age. Returned them for a discounted pair of C1's and a pair of shoes to be named later (Rincon maybe?).

Sam, I always look forward to the reviews and love the website. Keep up the great work!

Sam Winebaum said...

Hi Josh,
For me both 1080v9 and Carbon X would fit the bill. most of my runs are somewhat slower than yours. If you want some excitement go Carbon X, if you want a safe and capable choice 1080.

Sam Winebaum said...

HI BQ Trail Runner,
Sorry they did not work for you. Some report achilles issues with them. For me none at all. The heel does start to get in the way at faster paces, sub marathon to half for me.
Curious what shoes work well for you now?
Thanks for your kind words about RTR. Much appreciated by me and team.
Sam, Editor

BQ Trail Runner said...

Hey Sam, currently use Clifton1/EpicReact2/Ride7 for slow and long runs, Boston 6 for speed work, Pegasus Turbo for marathons and marathon paced training runs, and Kiger5/ChallengerATR5/Caldera3 for trails and 50k's. Because of a neuroma, I need a wide toe box and soft forefoot. As such, the C1 barely makes the cut but if I skip the lower two eyelets and do a little surgery, I can widen the box enough to make them work.

Nick Purdy said...

FYI sizing for people. I ordered a 12.5, am a 12.5 in the Nike 4%, turbo, pegasus 35, zoom fly, etc. But the 12.5 was just too large overall. Almost fit like a 12.75 to 13. Had to send them back.

Anonymous said...

Sam, how cushioned do you find the Carbon X compared to the NB 1080 v9 when landing harder on the heel? At slower paces, I tend to land harder on the heel and want a shoe that can absorb the impact. I'm currently using the Vomero 14 as my slower pace shoe and I find it quite harsh on heel landings at slower paces (slower than 8:30 pace). It seems to work well at faster paces (lower 8s and below) but is surprising harsh for me on easy runs or recovery runs. My ankles feel beat up and sore with the Vomero. The 1080 v9 seems to have a softer and more cushioned heel than the Vomero (at least based on a short run at the store) and the Beacon also seemed to work for me. Oddly, I don't find the Zoom Fly Flyknit to be nearly as harsh as the Vomero 14 at slower paces even though it is an uptempo shoe. How would the Carbon X compare in terms of absorbing harder heel strikes and helping to roll that energy forward?


Sam Winebaum said...

Hi Josh,
Carbon X is very well cushioned at the heel but the drop plus the plate has me leaning to say that it would "feel" less cushioned than 1080v9 at slower paces. Carbon X I think could use more drop to drive forward at slower paces and faster paces as in the review. This said you find the Beacon works for you and I find it to have a low heel and while cushioned quite a bit of rear shock at slower paces. Vomero I might guess what you are feeling is not the overall cushion but the effect of those stabilizing side walls at slower paces, digging in a bit? I can feel them a bit too but no issues. 1080v9 heel I do find overall slightly better cushioned than Vomero but not nearly as dynamic as Vomero at the forefoot when pace picks up. Carbon X has been fine at slower paces but prefer it for tempo or near tempo paces where I am more off the heel and can really use the rocker. We will be updating our Carbon X review with two more testers including one who actually ran in the Project Carbon X race on a 10 x 10km team.
Sam, Editor
Thanks for reading Road Trail Run! See our page with links 100’s of in depth shoe and gear reviews HERE. You can also follow RoadTrailRun on Facebook, Twitter, YouTube and Instagram where we publish interesting run related content more frequently as well as links to our latest reviews.
Shopping through links on articles help support RoadTrail Run and is much appreciated!

MechaDriver said...

Just received my Carbon X today. Noticed that the left foot weighed (in a size 9) 8.5oz while the right foot was 8.9oz. Should I just be happy that I got a lighter left shoe or might there be a manufacturing defect? The initial fit and rocker/bounce seemed spot on.

Sam Winebaum said...

That’s quite a difference and below our estimated weight which is about at your weight for a 9. Can you spot any differences? Sockliner? Sam, Editor

Snow said...

Thank you for including a legitimately larger person on your testing panel, applicable insight for those of us lacking willowy builds.

JKC said...


Yeah, that does seem like a big weight difference between shoes.
The two biggest differences I've ever come across are...
Clifton 6 . .25 ounce difference
Ghost 11 .27 ounce difference

I iniitally got spooked by both of these, but then realized that if I wasn't a nutcase that weighed and logged data for every shoe I run in, I would probably never know and just run on happily. Unless you can feel/see a difference, maybe don't sweat it.

MechaDriver said...


So I got my replacement pair. Both shoes are 8.5 oz for a size 9. I didn't have a chance to look at the original shoes with the weight difference in more detail, since I packed them up and sent them back. I have seen other shoes with up to a .2 oz difference, but never a .4 oz difference.

MechaDriver said...

So, I have 3 runs of 7 miles each in the Carbon X and I am not feeling much of a pop. Additionally, I have soreness in the shin and calf. I have run in an escalante (0 drop) and in both the zoom fly FK and vaporfly FK (stiff carbon fiber shoes) and haven't had this problem. I don't normally run in Hoka's, so was wondering if I need to give the shoe more time for me to acclimate? My paces have varied from 10:00 min/miles down to 8:00 min/miles.

Sam Winebaum said...

Hi MechaDriver,
Sorry to hear about Carbon X issues. I had only very minor calf soreness during early runs in them and none to shin. I ddi find they took around 20 miles to settle in, What paces did you run those 7 milers at? Are you in a heavy cycle of training and what have you been training in. All of my running in them in has been your pace range. The geometry of the plate is very different than VF or ZF and the drop is lower in Carbon X leaving aside the escalante so it may be the flatter profile in the shoe of the Carbon X plate doesn't agree with you gait style.
Sam, Editor

JimO said...

AS a runner that have the VP, Carbon X and %Next, the Carbon X seems to be a good shoe for longer, faster paced miles. Get around 8:45 and up and it gets clunky and I seem to feel the weight. The %Next is in a class of its own and Carbon X can't even get close. For racing, I would still choose the VP or %Next over the Carbon X in the marathon distance. Nothing to even debate. 50k road or further, I might consider the Carbon X but it sure feels heavy in those later miles of a 20+ mile run. Just my thoughts as a 145lb, 56yr old 40-55mpw runner. Jim

BoulderMike said...

Just finished my first run in the Carbon X. Generally I don't like maximal shoes, or rocker (I HATED the Rincon!), but I really enjoyed the Carbon X. I immediately felt the pop and they seemed to be pushing me forward from the first step, in a good way. I generally wear 4mm heel to toe drop shoes, with low stack heights like the Razor 3, and have been working in 6mm drop shoes like the FuelCell Rebel. I like the Rebel but the issues with lack of traction in wet conditions concerned me as I am looking for a shoe for the Chicago Marathon. I don't really like the Razor 3 enough to use it. The Rebel has worked well on long runs, but the traction issue concerns me. So, I thought I would try the Carbon X. At this point it seems to be a winner. It propelled me forward in a good way, unlike the Rincon which felt like I was on a trampoline, pushing me upwards not forward. The fit was good, true to size. My mens size 9.5 both weighed exactly 8.9 ounces, which is a bit heavy for me, but I didn't notice any issue during my run from the weight. Honestly the only issue I had was later in my 6 mile run I felt a bit of a hot spot on the bottom/ball of my right foot, just behind the big toe. Not bad, but something to pay attention to. I probably need to adjust the lockdown. If that is the only issue, and I can correct for it, I am certain I will use it this Sunday for my 20 miler, and if that goes well for the race.

Sam Winebaum said...

Thanks for the insights Boulder Mike.
I too found the Rincon a bit to vertically bouncy.
Focus on the groove during your 20 mille run. You will find it. A bit flatter feeling than say a VF but propulsive. Best of luck in Chicago!
Sam, Editor

BoulderMike said...

Update since running 20.5 miles last Sunday, and 6.18 yesterday:
I dialed in the fit by moving the top lace (by the ankle) to the last hole from the second to last hole) and didn't experience any hot spots. But, after yesterdays run I noticed that the right shoe seems longer than the left and that is what was causing the hot spot and the general feeling of fit issues with the right shoe only. The left shoe seems perfect. On the right shoe my foot seems to be further back in the shoe and so the wider part of my foot is back further causing the ball of my foot to feel like it is on the hump of the footbed and on the narrower part of the shoe. Not sure if this makes sense. And, starting yesterday after my first run after the 20.5 miler I have had a bit of a twinge/pain in my right lower back. Seems maybe the right shoe is defective in sizing and could be causing the lower back issue.
Chicago is coming up and I am worried that I haven't found the right shoe. I am thinking either I return the Carbon X and forget about it, even though I really enjoy how they run, or possibly see if Hoka wants to exchange them for another pair which hopefully doesn't have the right foot issue.
Bottom line is I don't know if the right shoe is defective or the shoes just don't fit right for me. It isn't an issue caused by my feet being different because I don't have this issue with other shoes.
Currently I am struggling deciding on a shoe for Chicago. I have run some longer runs in the Razor 3 and it just hasn't felt good enough for me to choose it for certain. I have also run up to 18 miles in the FuelCell Rebel and that was the best option yet. I am getting older and I think maybe the Razor 3 just isn't enough shoe for me for marathons anymore.

Kessilrun said...

I'm in the size 10 (US), and 130lb. I don't get any sort of pop, as some described, nor do I notice any mush, squish, or bounce. It might be because I'm so light(?). However,the running economy is great and completely noticeable. My Nike Turbos are much more poppy, but lack the roll-off I've already become so dependent on with the Hokas. If only these Hokas could have the reactive pop my Turbos do...or if my Turbos had a more aggressive rocker, the perfect shoe would be born. The thin upper mesh will undoubtedly be welcomed in the summer months, but in the Iowa cold that is already hitting us (with the recent 7 degrees wind chill), my feet were way too breezy and chilly.

Olivier Thiriet said...

Hi, I've been reading most of your tests, and I love it!
Any chance to see the new Hoka One One Rocket X tested soon?