The On Cloudboom Strike LightSpray isn’t for sale yet, but I managed to get a pair to test. They’re great—light, fast, secure feeling—now that I’ve performed a little surgery. Here’s what I had to do to the exciting new marathon racing shoe.
On Cloudboom Strike LS
Pros
- Unique upper created by a robot
- The Best New Shoes You Can Buy Now
- Its not so easy to cut through the upper, even with an X-Acto knife
Cons
- oz mens 12
- Can't adjust fit
- Credit: Trevor Raab
| Type | Marathon Racing |
|---|---|
| Weight | 8.0 oz (men’s 12) |
| Heel Height | 39.5 mm |
| Forefoot Height | 35.5 mm |
| Drop | 4 mm |
What Is LightSpray?
You’ve probably seen the new shoe on Instagram or Facebook. The company, On, set the running world abuzz when it displayed a robot that spun and twirled a shoe around while it sprayed a plastic material that would become the shoe’s laceless upper. The process takes just three minutes per shoe and, when done, you’re handed a shoe that’s still warm. Think of it as a highly precise hot-glue gun. And, that’s exactly how it began. Somebody at On saw a video of a Halloween toy that used a hot glue gun to shoot spiderwebs. So, they evolved the concept and built a machine that could print a one-piece running shoe upper.
During the DAA Industry Opt Out weekend, On set up the robot in a storefront in the SoHo neighborhood to show off the technology and let runners try on demo pairs.
The first shoe to get the technology is On’s top marathon racing shoe. The Helion HF Hyper midsole is a Pebax-based foam which delivers a relatively firm underfoot feel among super shoes, but feels superbly responsive and fast.
How to Put It On
This is probably the biggest question you have at this point: How do you get your foot inside? After all, without laces, you gotta do some wiggling. I like to say that it’s like putting a bike tire on a rim, if you’ve ever had that experience. You start at the front, work around both sides of your foot at the same time, pulling up the heel last. First, slide in your foot as far forward as it will go, then use your fingers to coax the upper up around your ankle. But, don’t use your fingertips—the demo pair I tried on in NYC had a hole where people’s nails had ripped through the thinnest part of the fabric.
It’s a snug fit—the first time I put on my brand new test pair, I had to struggle with it quite a bit more than the demo shoes that had been tried on by who knows how many other runners before me. Once on, it pressed so snugly to my feet that you could see extensor hallucis longus tendon (the one that runs along the top of the foot to the big toe) flex beneath the plastic. That snug fit continues on the run, as I felt completely locked in to the shoe, even when rounding turns. If I didn’t know any better, I’d swear there were shoelaces.
Im a firm believer in.
Is It a Custom Build?
Well, no. And that’s what can be problematic for some runners. Hellen Obiri, the 2024 Boston Marathon champ, might have a pair that’s molded to her foot. But, for now, that’s not happening for you and me.
It would be a mighty expensive proposition for On to roll out robots around the country, scan feet, build shoe lasts, and try to customize the fit. And, frankly, that cost isn’t worth it when the overwhelming majority of runners fit neatly enough into the existing half-size shoe model.
But, while we wait for a future where such customization is possible, we can imagine that On might set up shop in places around the world to speed up production more locally and reduce its carbon footprint by not having to ship boxes of shoes from the other side of the globe.
Even so, while the flexible material didn’t pose any problems on an initial jog, I had a searing pain at my lateral malleolus—the bone that sticks out of the ankle—on my right foot. But it was only at that one spot on my foot, so I joked that, because the robot is precise, it was probably my parents’ fault when they built me.
Break Out the Knives
To be fair, I could probably fight my way through it, deal with the irritation for a few runs, and hope the upper stretches a little to break in. (When breaking in a pair of Red Wing boots, I had to wear wristbands around my ankles for weeks to ease the pressure until the leather gave up the fight!) But, why do that when I can seek a quicker fix with an X-Acto knife?
I’m a firm believer in modifying your shoes if you find that there’s something not quite right. For example, every runner should own a hole punch in case you need to relocate or add eyelets to a pair of shoes. On the original Nike Vaporfly 4%, I had terrible rubbing at the top of the eye row of my left foot. But, by shifting the eyelet back just a little, the pain was gone and I wore that pair for many races. Other runners make more drastic mods like cutting open the toe boxes to reduce the risk of blisters or even shaving away foam and rubber to help improve how the shoe lands for them.
Cutting the upper on the LightSpray shoes, I hoped, was going to be a more straightforward operation than on fabric uppers. After all, the plastic is laid down in molten threads that harden and fuse into a single layer. So, when I trimmed the collar, the material wouldn’t fray. My only concern would be whether doing so would leave a thicker, rigid edge that may rub in a different manner.
When we shot video and photos of me doing this, I had forgotten my fabric rotary cutter at home, so I made do with a pair of scissors and X-Acto knife. The rotary cutter definitely makes the process easier and makes the rounded cut conform more readily.
First, I slipped the shoes on to gauge just how much of the material I’d need to remove. Because there are no laces and support is built into this bootie hugging the back of the foot, I didn’t want to take off too much and wreck the fit. I drew a light line that curved just below the troublesome ankle joint.
After taking the shoe off, I supported the upper material on a scrap block of wood. Use something like this yourself so you don’t accidentally cut into the other side of the shoe or your table top.
The X-Acto knife might have worked, but the shoe was at an awkward angle for cutting and I didn’t have much material to hold onto because I was making such a slight shaving at the top. So, I ended up just grabbing a pair of scissors in the RW Shoe Lab. It worked okay, but I had to take a couple passes to make sure I had cut a smooth line without any jagged edges that could inadvertently turn into saw teeth in the middle of a run.
I slipped the shoes back on to test the fit, and the pain was gone. But, later, on a test run, I could still feel a bit of irritation from the top edge of the bootie, so I lowered it further. This time, I used the rotary cutter, which made the process safer and cleaner.
When Can You Experience LightSpray?
While Obiri has been wearing the shoe since her win in Boston last April and On officially announced the technology over the summer, you have to wait a bit longer to get it on your feet. How long? Well, we don’t have a good answer for that, unfortunately. We’ve been told that there’s not yet a date for commercial availability, but that there will be “another drop in 2025.” The best thing you can do is head on over to on.com/lightspray and click the “Be the first to know” button to get notified.
Why Trust Us Runner's World, guiding the brand's shoes and gear coverage. A true shoe dog, he's spent more than a decade testing and reviewing shoes. In 2017, he ran in 285 different pairs of shoes, including a streak of 257 days wearing a different model.
