On Cloudboom Strike LightSpray First Run Review: On's Lightest Racing Shoe Yet

Introduction

The On Cloudboom Strike LightSpray is the LightSpray version of the Cloudboom Strike, and the difference is the upper. It is produced by a robot, weighs a lot less than the standard version, and pushes the price up to $330 or €330. In our UK size 9, the shoe weighs just 192g or 6.8oz, which puts it among the lightest shoes we have tested over the past year. The only shoe lighter in that period was the Metaspeed Sky Paris.

The rest of the platform is familiar territory: the same 4mm drop as the standard shoe, a 39.5mm heel stack, and a 35.5mm forefoot. This review covers our first run in the shoe, a session built around two 5K efforts at around marathon pace sandwiching a park run.

The LightSpray Upper

The LightSpray upper is the star feature of this version. It is a one-piece upper made by a robot in a three-minute process, using 1.5km of filament material wound around a last. There is no glue and no seams, and it is bonded to the midsole using thermal fusing technology. The material is also recyclable, which reduces waste.

The result is a bootie-style fit that is very close and snug, and incredibly lightweight. It is the style of shoe worn by Hellen Obiri when she won the Boston Marathon, and we expect to see it at the Olympics as well. Compared with the standard Cloudboom Strike upper, it makes the shoe significantly lighter while keeping the same fit character underneath.

Fit: Tricky On, Excellent Once On

The first thing to know is that this shoe is quite hard to get on the first time out. We were wary of pulling too hard on the material, but it proved to be quite hardy, and it does need a firm yank to get your foot in because the fit has to be secure and tight for racing. We have also seen comments suggesting it as a triathlon shoe, but pulling it on like this would be a nightmare in transitions, so we are not convinced that is the way to go.

Once on, though, the fit is genuinely excellent. It has a second-skin feel with no pressure points, no rubbing at the Achilles, and no hot spots around the front of the foot. In a UK 9, which is our normal size across all On shoes, the foot stayed locked in through sharp turns with no sliding forward, backward, or side to side.

Underfoot Feel and Propulsion

Underneath the upper is the same setup as the standard Cloudboom Strike: two layers of On’s Helion HF hyper foam, a PEBA-based foam that is On’s bounciest, with a carbon speedboard running between the layers. Your foot sits directly on the foam, with no sock liner beneath it. There is a rubber outsole with good coverage on the forefoot and heel, and more rubber than the Cloudboom Echo, which had durability problems in our testing.

On the run, the ride is certainly bouncy, and it feels slightly more springy than the Cloudboom Echo 3, which was more of a rocket of a shoe. This is more of a sink-and-punch feel with propulsion, and it works well. It is easier to get propulsion from the plate and foam here than it was on the Echo 3, even for a runner who is not a big bounding runner. On uphills, the light weight gives a nimble, punchy turnover.

How It Held Up Late in a Hard Session

The most striking thing from this first run was how the shoe behaved when fatigue set in. In the final kilometre of the park run, and again in the last few kilometres of the second 5K, the shoe made it easier to maintain a controlled, efficient stride and hold pace even when things were really hurting. That is not something we have experienced with On’s earlier carbon shoes, including the Echo 3.

The overall session, two 5K efforts at marathon pace around a park run, produced solid splits, and the shoe helped rally pace back in the closing kilometres after a rushed, badly warmed-up start. It is a fair call to say this is On’s best racing shoe yet, and a clear upgrade on the Cloudboom Echo 3 in materials and design.

Things to Consider Before Buying

Durability is the big open question. After one run, we cannot judge how the LightSpray material holds up, and any stretch in the upper over time would be a problem. The rubber outsole coverage looks promising relative to the Echo, but only more miles will tell.

Price is the other consideration. At $330 or €330, this is a big outlay over the standard Cloudboom Strike, and the carbon super shoe market is extremely competitive. When excellent racing shoes are available for considerably less, it is hard to justify the step up to the most expensive models unless the weight saving and that upper genuinely matter to your racing.

Buying Advice

If you are a racer who values every gram, the LightSpray version makes a compelling case. The weight saving comes entirely from the upper while the midsole stays the same, and on this first run the lighter feel clearly played a role in how the shoe performed late in a hard effort.

Sizing matters here: our normal On size delivered a really good fit with no looseness, so sticking with your usual On size is the safest bet. If you struggle with regular uppers, the seamless, glueless design may be a genuine solution, as long as you accept the tricky entry process and the premium price.

Conclusion

After one run, the On Cloudboom Strike LightSpray looks like On’s best racing shoe to date. The robot-sprayed upper delivers a seamless, second-skin fit at a dramatically low weight, the Helion HF midsole and carbon speedboard combine for an easier-to-engage, bouncier propulsion than previous On carbon shoes, and the whole package is a lot of fun to run fast in. The price and the durability question are the two things to weigh up, but as a first impression of a premium super shoe, this is a big thumbs up.