On reveals ‘LightSpray’ technology on Cloudboom Strike LS
Weight: 188g (UK 8.5)
Stack height: 39.5mm (heel), 35.5mm (forefoot)
Drop: 4mm
The shoe
Following months of secrecy, Swiss sportswear brand On unveiled its revolutionary new LightSpray technology earlier this summer: an ultralight, one-piece upper that’s sprayed onto the shoe by a robotic arm.
While 2023 might have been the year of the midsole, in 2024, the upper has had a moment. LightSpray is made in a fast, one-step manufacturing process, automated by a robotic arm at the On Labs in Zurich. It’s ultra-thin, adaptable to the foot, seamless and lace-free. And, according to On, each shoe is fully assembled in just three minutes.
But those aren’t the only benefits. On claims the technology reduces an upper’s carbon emissions by 75% compared with its other racing shoes.
‘LightSpray marks a significant milestone for On, not only in creating high-performance products but also the potential it has to move us towards a more sustainable, circular future,’ says Marc Maurer, co-CEO of On. This is thanks to the upper’s construction from a single recyclable material and the assembly process that eliminates the need for glue.
The Cloudboom Strike LS (LightSpray) is the brand’s first high-performance running shoe to feature the technology. Weighing in at just 188g (UK size 8.5) – including a 30g upper – Hellen Obiri wore a development version to win the 2024 Boston Marathon in April and placed second in the shoe at the 2024 New York City Marathon.
The non-LightSpray version (with a technical mesh upper) is already widely available, but the LS isn’t set to launch until later this year. I was one of five lucky people in the UK to get their hands on a pair ahead of their launch and understandably, I’ve been asked a lot of questions about them: How do they really fit? Do they really feel stable? Are they breathable?
Having tested the shoe over the past couple of months, here’s my verdict.
How does the Cloudboom Strike LS fit?
I’m usually keen to get onto the midsole as quickly as possible when it comes to reviewing a new running shoe, but, let’s face it, the upper is the star of the show here and fit is the question on everyone’s lips with the Cloudboom Strike LightSpray. With no heel counter, no lacing system and no overlays, you’re relying purely on the upper moulding around your foot in order to get a secure lockdown.
I won’t beat around the bush – this isn’t the easiest shoe to get on, especially with no heel tab. But, then again, a shoe with no laces needs to be tight in order to secure your foot in place, which is why the opening is very narrow. I’ve found if I insert my foot slightly sideways into the shoe until about halfway, I can get two fingers down the back to pull the heel out slightly (the material has a tiny bit of give) and then wriggle/dance my foot forward until it slips in. If this sounds like a faff, remember, you’ve got no laces to tie: I timed it and it took me approximately 11.19 seconds. For comparison, the Alphafly 3 took me 16.14 seconds to get on.
Now, I had all the same questions everyone has when it came to the upper. Namely: 'How on earth is this going to hold my foot in place?’ Well, folks, trust me when I say: it just does. The technology comfortably moulds around my foot, with no stretching, slipping or instability. It’s weird, but it’s also pretty cool.
However, it’s worth noting that I have a pretty average foot – I wear a UK 8.5 in almost all of my running shoes, including On, and the Cloudboom LightSpray is no exception. If you do have a wider or narrower foot, I can’t say whether the technology will mould around your foot as well. Perhaps in the future, On will look to personalise the shoe to more foot types. For now, we’ve just got this standard option and I’m lucky that it works fine for me.
The LightSpray material itself is surprisingly strong – after three months running in these, I’ve not seen any sign of tearing or stretching. They still hold my feet in place just as well as the first time I put them on. Breathability hasn’t been an issue for me either.
Oh, and in case anyone’s wondering – when it came to the ‘socks or no socks?’ question, I took Obiri’s lead with these and opted for my usual quarter-length number.
What’s the Cloudboom LightSpray like to run in?
The shoe’s midsole (39.5mm/35.5mm, 4mm drop) features two layers of Helion HF Hyper foam, a Pebax formula made with over 40% bio-based raw materials, and a Speedboard – On’s version of a carbon plate – sandwiched between the foam to aid propulsion.
The ride has that bouncy and propulsive feeling you’d expect from a carbon-plate shoe and you can really feel the responsiveness – way more than the Cloudboom Echo 3 which felt a lot stiffer and harder work. At the same time, it’s not aggressive like the Saucony Endorphin Elite or even the Hoka Cielo X1. In fact, it probably leans more towards the Asics Metaspeed Paris models (188g) on the Vaporfly 3 (198g) in terms of that light, on-the-foot feeling and like the Metaspeed Paris models, the lower heel-to-toe drop is probably going to be a smarter bet for forefoot strikers and midfoot runners.
Like a lot of On’s running shoes, I would say that the Cloudboom Strike LS feels slightly firmer underfoot. That’s not a criticism, though – it’s not uncomfortable or harsh, it just offers a solid platform for push-off and there’s still a decent amount of cushioning overall to see you through a half marathon or marathon.
The main catch of the shoe, though, is the price. At £330, this is one of the most expensive racing shoes on the market, second to only the Adidas Adios Pro Evo 1. I never thought I’d be using the words ‘Alphafly’ and ‘cheap’ in the same sentence, but even Nike is going to be a more ‘affordable’ option here.
RW verdict
While you can make assumptions all you want, the On Cloudboom Strike LS is undeniably a trailblazer and, having run in the shoe over the past few months, I believe that the brand has delivered an impressive innovation with its LightSpray technology. Yes, getting the shoe on might take some getting used to, and I’m definitely fortunate to have more of a ‘standard’ foot shape to accommodate the technology, but the ultralight one-piece upper moulds closely around the foot for a secure lockdown that defies doubts about stability or slippage.
Performance-wise, the midsole delivers a bouncy and propulsive feel without veering into an overly aggressive or rigid territory. And while these definitely aren’t made for easy runs or gentle plodding, you don’t need to work as hard in them as the Cloudboom Echo 3.
But are they worth the £330 price tag? The jury’s out on this one. Sure, it’s a great shoe that’s fun, bouncy and lightweight – but so are the Metaspeed Sky Paris (£220) and the Vaporfly 3 (£239.99). Plus, these two shoes have been hitting the podiums of the Majors this year as well.
The Cloudboom Strike LS is undoubtably On’s best racing shoe yet, but it’s a concept shoe, designed for tech-minded racers with a budget to match. If you can forgo a few extra grams, I’d probably tell you to spare your money – and your curiosity – and opt for a more ‘affordable’ speed shoe instead.
If you’re not quite on board with the Cloudboom Strike LS, but still want to experience many of its assets, then here’s presenting On’s Lightspray-free Cloudboom Strike. Rachel Boswell, RW’s Senior Content Writer, gave this same-but-different race day shoe a spin – and shared her thoughts below.
Cloudboom Strike review
Weight: 219g
Stack height: 39.5mm (heel), 35.5mm (forefoot)
Drop: 4mm
The Cloudboom Strike is undeniably a sibling to the Cloudboom Strike LS. It boasts the same stack height and drop, the same colourway and, as with the Cloudboom Strike LS, its job description is to deliver top-end speed for races and speed sessions, without skimping on comfort.
However, the shoes are not identical twins. For a start, the Cloudboom Strike is slightly heavier in weight – but it’s less hefty when it comes to price, retailing at £260. There are also obvious differences when it comes to the upper. Unlike the Cloudboom Strike LS, which boasts a flamboyant, lace-free Lightspray system, the Cloudboom Strike looks like an ‘actual’ running shoe with – shock – real laces that you can tie in a regular fashion. This is an automatic win if convention is your thing.
Still, the Cloudboom Strike’s mesh upper both looks cool (check out those proud-to-be-Swiss-made details) and, in my opinion, does its job exceedingly well. Made from a single piece of semi-transparent material, it securely locks down my narrower foot without feeling stuffy or restrictive, allowing my foot to breathe and feel relatively relaxed while wearing them for interval sessions.
I also rate the cat tongue feature around the heel and the grippy sections inside the shoe and along parts of laces, which together keep my feet, and running socks, in place on the move. There’s no awkward slipping here – just a whole lot of effortless speed sealed up in a clean-looking, comfort-giving shoe.
Talking of comfort, let’s move to the plush, removable Bounceboard – an On innovation made of Helion hyper foam. A bit like a supercharged insole, this Bounceboard strikes a brilliant balance between plushness and efficiency, which pushes you forward powerfully but pleasantly while running in them at greater efforts. Maximal energy return and comfort? I, for one, am here for it.
But that’s not all. Nestled directly underneath the Bounceboard is the carbon plate – a spoon-shaped Speedboard that absorbs energy and channels it through the forefoot, leading to more powerful take offs that I definitely notice and really enjoy. Although not as pronounced here as in other On shoes, the unique CloudTec elements in the midsole also help the shoe to adapt to your individual running style and movements, all the while giving you a softer and smoother ride. For me, the midsole felt firm enough to be snappy and rapid, but just about spongey enough to be kind on my feet over longer distances and speed sessions – which is ideal in light of my high-mileage tendency.
Lightweight and responsive with a pronounced rocker geometry, this carbon plate race shoe is, in summary, like a coiled spring that fires into action on the roads. So, if the Cloudboom Strike LS isn’t to your taste, you should certainly give the Cloudboom Strike a chance.
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