Nike Alphafly 3 vs On Cloudboom Strike LS: Two of the Best Carbon Plate Racing Shoes Compared

Introduction

The Nike Alphafly 3 and On Cloudboom Strike LS sit at the top of the carbon plate racing shoe market right now, and they are also two of the most expensive options in the category. After more than 150k of running in both, plus a few races in each, both have earned a place among the best carbon racers their brands have ever made.

This comparison looks at how they differ in design, fit, and ride feel, and which one makes more sense depending on the distance you race.

Specs at a Glance

The On is the lighter shoe at around 6.8 oz, compared to 7.7 oz for the Alphafly 3. Drop differs too: 8 mm on the Nike, 4 mm on the On. Price runs in Nike’s favour, which is unusual: the Alphafly 3 costs £285 or $285, while the Cloudboom Strike LS is £330 or $330.

Nike Alphafly 3: Design and Construction

The Alphafly 3 uses a ZoomX foam midsole, Nike’s bouncy PEBA-based foam, with a carbon plate sandwiched between two layers of it. A visible midsole cutout shows off the carbon plate and helps trim weight, and a forefoot air pod adds a more responsive feel at toe-off. The upper is Atomknit 3.0 with a bit of extra padding around the heel, and the rubber outsole offers good forefoot coverage plus some rubber at the heel. Durability and grip have held up well.

On Cloudboom Strike LS: Design and Construction

The most eye-catching part of the Cloudboom Strike LS is its Lightspray upper, a one-piece sock construction attached to the midsole by machine. That upper is the main reason this shoe is so much lighter than the standard Cloudboom Strike.

Underneath, the midsole uses Helion HF, On’s best PEBA-based super foam, with a carbon Speedboard plate sandwiched between two layers of it. The rubber outsole has good coverage on the forefoot and heel, and there is no big midsole cutout, which is a little surprising for a shoe this light given how common that weight-saving trick has become.

Fit and Sizing

In both shoes a UK 9 worked well, which translated to a US 10 in the Nike and a US 9.5 in the On. The Alphafly 3 fits securely and comfortably, with the Atomknit upper holding the foot locked down on fast runs and a well-designed heel that avoids the irritation the thin padding strip on some Nike racing shoes can cause.

The Cloudboom Strike LS also fit well with no concerns, holding the foot in place without looseness and showing no stretching after 150k. It creates a barely-there feel that suits racing. The caveat is that the one-piece upper is riskier: there is no lace-based adjustability, so if the fit does not work for your foot shape, you cannot tune it the way you can with the Nike. For a narrower foot it worked very well, but it will likely divide opinion more than the more conventional Atomknit upper.

Ride Feel: Bounce Versus Turnover

Running in both shoes back to back makes the contrast clear. The Alphafly 3 delivers much more squish and bounce, with the classic loud, slappy Alphafly ride: a soft landing at the heel, then a firm, punchy forefoot that pushes you forward hard. The continuous midsole design creates a smoother, faster transition, and the big ZoomX stack gives strong propulsion with a responsive toe-off.

The Cloudboom Strike LS is not as soft and does not sink as dramatically, but it offers lightning-fast turnover and a very responsive feel off the toes. It feels nimble and light, almost like skipping along the ground, with the foam and plate returning pace efficiently. It is a different ride, but a very fast one.

Race and Distance Notes

The Alphafly 3 has shed weight compared to past versions and turned into a genuine all-distance racing shoe. It has world records to its name at the marathon distance, and a 10K PB has been set in it, but it now carries a snappier, almost Vaporfly-like edge while keeping the cushioned Alphafly character. It excels over long distances thanks to that extra comfort.

The Cloudboom Strike LS is a major step forward for On’s carbon racing shoes. It performed excellently in a half marathon, making it easy to keep turnover high and pace fast in the second half, and it held up well over a 20-mile training run. As a marathon racer it is likely excellent, though some runners may want a touch more protection than it offers at that distance.

Which One for the Marathon?

For marathons in particular, the Alphafly 3 is the more risk-free choice. The extra cushioning gives a more protective feel without costing pace, because the foam rebounds and returns energy effectively, and it remains a strong short-distance racer too. The On will work brilliantly for many runners at all distances, and it has produced impressive marathon results for unsponsored athletes, but the Nike’s added comfort and its adjustable, more universally forgiving lace-up fit make it the safer pick for the general runner heading to 26.2.

Verdict

This comparison is genuinely tight, which would not have been true of an On versus Nike carbon shoe matchup in the past. The Cloudboom Strike LS is lighter and delivers a more direct, lightweight feel, though it is a touch firmer and perhaps not quite as explosive as some top-tier rivals.

The Alphafly 3 wins overall thanks to its lower price, a fit that will work for more people off the peg, extra cushioning for longer races, and the classic big-bounce super shoe ride in a still very light package. If you prefer a firmer, more nimble feel, the Cloudboom Strike LS is a fantastic alternative that more than earns its place alongside it.

Conclusion

Both shoes represent the peak of what their brands have produced in the carbon plate category. The Nike Alphafly 3 is the more versatile and protective all-distance racer, while the On Cloudboom Strike LS rewards runners who want minimal weight and rapid turnover. Match the shoe to your foot shape and target distance, and either choice will serve you well on race day.