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Track & Cross Country Running Shoes • February 20, 2024

Hoka Cielo FlyX Review: Gonna Fly Now

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What You Need To Know


5.8 oz. (164 g) for a US M9 (unisex sizing)

Stack Height / Drop

25 mm in heel (no forefoot measurement given)

Best For

Track races from 1,500 m to 10K

Key Features

Engineered mesh upper, PEBA midsole, 6-pin composite spike plate

On The Run
Plenty of bounce for long races Six-pin plate has tons of grip Swap the laces for real fast races


Introduction to the Hoka Cielo FlyX

KALEB: Believe in the Run focuses largely on road and trail running shoes, which makes sense because those are the largest markets. Sometimes, track spikes fall through the cracks simply because brands aren’t constantly trying to hype them to the public as much as they are the latest tempo shoe or marathon racer.

Consequently, Mercer and I have compiled a list of spike releases we’re drooling over (creatively named Kaleb and Mercer’s Drool List by yours truly) so that we can semi-regularly remember to bug Robbe to toss a carbon-plated bone or two our way.

I honestly wasn’t expecting it to work, but then Our Blessed Seeding Lord Robbe added us to review the Hoka Cielo FlyX, one of the spikes on the list. So… I guess we ball, as the kids say. (I am one of the kids, and that felt forced even for me, so let’s just move on).

The Cielo FlyX is Hoka’s new super spike, meant for elite-level performances from 1,500m to 10k. It sports a composite plate, six pins, and 25mm (yes, you read that right, an INCH) of PEBA-based superfoam. Understandably, this brings up the weight a bit more than your average track spike (almost 6 oz.), so my question going into this review was simple: does the FlyX have enough bounce to counteract its own heft?

MERCER: Given Hoka’s recent success in the high-tech racing market, it was only a matter of time before we saw an update to its Cielo X spike line. Sure, there have been updates to the Cielo X LD, but it’s been quite a while since we got anything truly inspirational from Hoka for the track. But now, with athletes such as Luis Grijalva and the rest of NAZ Elite performing well on the world stage, Hoka’s roster began looking for more from their spikes. And Hoka, being the OG “more” company, gave them a whole lot “more.”

In the Cielo Fly X, we get the new PEBA foam from Hoka’s other racers, like the Rocket X 2, combined with a composite plate that follows along with the likes of the ON 10K and Nike Dragonfly. It’s topped with a beautiful single mesh upper that looks like a weather report to tie it all together.

So, are we forecasting a significant spike? Or are we getting mid-Atlantic shitshow weather?

What we like about the Hoka Cielo FlyX

KALEB: My first run in the spike was right after a tough workout, so my first impression was defined by two things: comfort and weight. From step-in to lap 25, the PEBA superfoam underfoot is gloriously soft. Like, “I almost want to run an easy day in this spike” soft. On the other hand, running on tired legs, I couldn’t tell if there was enough response from the spike to keep the momentum rolling, and I couldn’t tell if the softness skewed into “mushy” territory.

Regardless, the word that kept turning over and over in my mind to describe the ride was “addicting”. Even tired, I kept running laps in the spike because it just felt so nice, fast or otherwise. So decided to bide my time and wait to pull out the FlyX until I was more rested.

And boy-howdy, am I glad I did.

An inch of foam is a lot underfoot for a track spike; heck, there are daily trainers and marathon racing flats with less cushion. And when that foam is supercritical PEBA, it changes the game.

Spikes, despite their limited space for different features, have a variety of ride-defining characters. Some spikes, like the Adidas Avanti TYO, are firm and snappy. Others, like the Saucony Endorphin Cheetah, have a pronounced pivot through the stride, rolling you forward before you’ve even realized you’re taking another step and speeding you up by increasing your footfall cadence. Still others, like the Nike ZoomX Dragonfly, have a pronounced bounce forward, focusing more on speeding you up by increasing the distance between each step.

The FlyX definitely falls into the last category. In my first true workout in the shoe — some quick, accelerative sprints — I was unsure how the soft, squishy midsole would do when trying to hit top speed as fast as possible, but my fears were quickly put to rest as the plate-and-PEBA combination slingshotted me forward.

The soft, strangely addictive feeling was still there, but it absolutely hummed with energy when brought up to speed. While I feel that this spike is best suited for 3k on up, rest assured that it’ll handle shorter distances just fine and will absolutely cooperate when it’s time to lay down those blistering closing laps of any race.

I won’t ignore the upper any longer: it’s gorgeous. I don’t just mean the “somebody took LSD and then tried to draw the shiny residue of an oil-covered rain puddle in a parking lot after spinning around ten times” colorway, either — the fit and comfort of the FlyX’s upper is unmatched. It’s silky soft, with just the right amount of stretch to keep you comfortable while also keeping you locked in over the relatively tall stack underfoot. It’s even vegan. Which. I guess is sexy now? I don’t know.

According to Hoka, the upper was designed with comfortable sockless racing in mind — if you’re kinky like that. I personally never tested this claim out, but knock yourself out, weirdo. Yeah, I’ll shame you for it, but that’s my prerogative one of the guys writing this review.

The laces are just as perfect: secure but gentle enough not to put undue pressure on the top of the foot when tightened. The toe box is accommodating without feeling sloppy if you don’t have Jarrett-esque proportions.

MERCER: Unlike Kaleb, I’ll start top-down and talk about the upper first. And unlike Kaleb, I run in spikes the way they’re intended to be run in with no socks. You can’t kink-shame me.

This upper is stellar. Every piece is thoroughly thought out and a delight to have on foot. The single-layer mesh feels like an absolute dream and looks just like one. It molds to the foot after a couple of uses and disappears on the foot; if you bring this spike up towards the upper ends of the track, like the 5k and 10k, the best thing you want is for the upper to make a magician and vanish.

The lacing system and collar also keep you locked down while being unbelievably comfortable. Hoka’s support starts with two pockets of cushion under the ankle like the Dragonfly to give some essential comfort, but it then takes a step above and lines the inside of the collar with a microfiber material to cut down on any blisters. It has worked flawlessly so far, I have done several workouts and races in these spikes and haven’t irritated my skin at all.

Bringing it down to that beautiful PEBA midsole, I was worried about it feeling too tall and mushy. And it was tall and mushy but in the best possible way. It felt like running on a trampoline; hell, it felt like running in a super shoe. And Kaleb said it best: it is addicting.

As stated earlier, the plate setup is nothing new, but the way it’s combined with the foam separates it from the On Cloudspike 10K and the Dragonfly; those spikes are faster now, with more snap and less bounce. The FlyX is all comfort, which means that during those later laps in a race, you’re feeling fresh and ready to start ratcheting the pace down.

Lastly, the composite plate and the grips on the back provide some excellent traction. Hoka stepped it up, swapping to a six-pin design compared to the four pins in the Cielo LD and MD.

Shop Hoka Cielo FlyX - Unisex

What we don’t like about the Hoka Cielo FlyX

KALEB: Honestly, I don’t have much to put here.

Sure, the spike could get away with being a little more aggressive, a little more stripped down, and a little spicier for the shorter distances, but that’s not really the point, is it? Especially for long-distance racing, aggressive ride character is less important than consistent, powerful energy return that doesn’t wreck the legs.

If you’re a 400m to 1,500m runner, maybe choose something with more pop, but if you’re looking for long-distance performance, Hoka has cooked up quite the dish in the Cielo FlyX.

MERCER: This shoe is all comfortable, and I love it, but there are some things that I want to be tougher, especially for race day. One of those is the laces. The laces are soft, slippery, and often untied, even if double-knotted. Something like the Metaspeed Sky+ has would be great for this spike — some “bite” to the laces, but they aren’t digging into the foot.

The tongue also feels like an afterthought on this shoe and is hard to adjust correctly; a gusset on the medial side of this spike would help get a correct adjustment on the tongue.

This last point may be my bad cause my dogs sweat like no other, but you can hear me coming from a mile away in these things, squeaking with my foot and the sole of the shoe. I haven’t found a way to get rid of it, and don’t tell me to wear socks. I guess I won’t be sneaking up on anyone in a race.

Shop Hoka Cielo FlyX - Unisex

Final thoughts on the Hoka Cielo FlyX

KALEB: For a while, Hoka (or Hoka ONE ONE, back in the day) was the king of max cushion. Then, the market adapted and punched Hoka right in its EVA-loving face, quickly outdoing the champ at its own game. Then, for a while, everything just felt like maximalism for maximalism’s sake, nothing more than a fad to sell more products.

Lately, however, Hoka has been reestablishing itself in the “oh, this is actually exciting” world with the Rocket X2, the Cielo X1, and even the Mach X. All three are shoes are heavier than most of the competition they share their respective spaces with, but they have so much sheer bounce and performance that it makes up for that weight.

Granted, some do that better than others, but the point is that this approach takes the fad and turns it into a tool, trying to place as much material as possible in all the right places to offset the problem that material would normally cause. Despite maximalism being the current trend, it feels new, it feels innovative, and I like that Hoka is finding a way to re-assert itself as the max cushion king in a world where everyone’s trying to set up their own Earldom.

All that to say, I think the FlyX fits right into this “purposeful maximalism” category. Sure, there’s a lot underfoot and sure, it boosts the weight a little bit, but even in a 3- to 10-kilometer race, where grams matter, the spike returns energy so well that it outperforms lighter, more stripped-down spikes. The amazing fit is yet another win in a world where race-day uppers can be stiff and uncomfortable.

For high-speed, long-haul races and workouts, I’m definitely excited to keep strapping on the Cielo FlyX this season.

MERCER: This spike is unbelievable, and Luis Grijalva will hopefully podium on the world stage with it. This spike works best from 3k up and can be brought down to 1500 if needed. If you want something like this spike but don’t rock with Hoka or the color, some alternatives are the NB LD-X and the ON Cloudspikes 10k (if you can find them).

You can pick up the Hoka Cielo FlyX for $180 directly from Hoka using the button below.

Shop Hoka Cielo FlyX - Unisex

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Kaleb Kabakjian
Track and XC Reviewer

Kaleb is one of the younger, “both of my knees still work” reviewers on the BITR team. As a high school cross country, track and field, and road racing athlete in Pennsylvania, Kaleb loves hearing about the latest endurance-athletics studies and seeing how everything out there can fit into a well-rounded training program. If you don’t see him drinking a weird health concoction or doing some strange warmup technique, he’s probably already started the race.

All-time favorite shoes: Saucony Ride 14, Nike ZoomX Dragonfly

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Fav. Distance

1 Mile

  • 1:18

    Half Marathon
  • 16:14

    5K (XC)
  • 4:30

  • 2:03

Mercer Alden
College XC/Track Reviewer
  • Strava
  • Instagram

Mercer is a collegiate athlete at the University Of Lynchburg, majoring in being awesome. He’s also extremely talented at folding shirts during GRIT packing at the Believe in the Run HQ.

All-time favorite shoes: Asics Gel-Kayano Lite, Hoka Clifton 6, On Cloudmonster

More from Mercer
Shoe Size


Fav. Distance


  • 57:50

    10 Mile
  • 15:55

  • 9:01

  • 4:35

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