Cloudboom Strike 2 vs Alphafly 4: Differences, Weight and Price

On's Cloudboom Strike 2 and Nike's Alphafly 4 are both thick carbon shoes for the full and half. Weights are 191g and about 188g, nearly even. The differences are the 5mm vs 8mm drop, and whether there are air units in the forefoot.

The Shoe Nerd's top pick

Choose between these 2 not by lightness but by "landing tilt." The weight gap is only 3g, but the drop opens 3mm. For someone who lands on the heel and rolls, the 8mm Alphafly 4; for someone who lands midfoot to forefoot, the 5mm Strike 2 gives each a natural tilt. The one you can buy in Japan now and adjust the fit of with laces is the Strike 2.

Key points

Weight: the Strike 2 is 191g, the Alphafly 4 about 188g (men's 26.5cm). A 3g gap
Drop is 5mm vs 8mm, a 3mm gap. The Alphafly 4 has 2 Air Zoom units in the forefoot
The Strike 2 went on sale on Jul 30, 2026. The Alphafly 4 in Japan showed "coming soon" as of Oct 18

What separates 2 shoes only 3g apart

When choosing a thick carbon race shoe, you look at weight first. Yet these 2 are 191g and about 188g. Try to decide by weight and you cannot.

The gap shows in the height difference between heel and forefoot (drop) and the contents of the sole. On's Cloudboom Strike 2 is 5mm, with a grooved sole and a carbon-blended plate. Nike's Alphafly 4 is 8mm and has 2 Air Zoom air units in the forefoot.

What is in each shoe is in the Cloudboom Strike 2 review and the Alphafly 4 review. Here I put the 2 side by side and decide.

What is the difference between the Cloudboom Strike 2 and Alphafly 4?

The Strike 2 is from On Japan official (Oct 18, 2026 listing) and the tech sheet. The Alphafly 4 is from Nike Japan official (Oct 18, 2026 listing) and the global announcement of Sep 17. Prices are tax included, and the gap is JPY 4,400 (39,600 − 35,200).
Item	Cloudboom Strike 2	Alphafly 4
Release date	Jul 30, 2026 (on sale)	Global announcement: early release Sep 17, wide release Oct 29. Japan: "coming soon"
Official price	JPY 35,200	JPY 39,600
Weight (one shoe)	191g	About 188g (men's 26.5cm)
Drop	5mm	8mm
Plate	Warped Speedboard blended with carbon fiber	Carbon Flyplate
Foam	Helion HF (a plate sandwiched between 2 layers of different stiffness)	ZoomX plus ZoomX LT (above and below the plate)
Air parts	None	2 Air Zoom units in the forefoot
Width and laces	1 type (regular), laced	1 type, Atomknit upper

If you pick just one row of the table, it is the drop. For 2 shoes close in weight and price, only here does a number that bears directly on how you run open wide.

Nike Alphafly 4

Before release: available from Oct 29

How do weight and stack differ?

Weight: The gap is 3g (191 − 188), about 1.6% of the Strike 2's weight (3 ÷ 191).

But the Alphafly 4's about 188g is a men's 26.5cm number. At 24cm it is about 157g, so 31g changes over 2.5cm, about 12.4g per cm (31 ÷ 2.5). The honest reading is that 3g under different size conditions is the same weight.

Drop: It differs by 3mm (8 − 5). The Alphafly 4 has the tilt with the higher heel.

The Strike 2's original 210g is from On's tech sheet (FW24). The Alphafly 4's previous generation is my estimate, back-calculated from the global announcement's "5% lighter."
	Cloudboom Strike 2	Alphafly 4
Weight vs the previous generation	−19g (210 − 191)	About −10g (188 ÷ 0.95 = 197.9)
Price per gram	About JPY 184 (35,200 ÷ 191)	About JPY 211 (39,600 ÷ 188)
Drop from the previous generation	4mm → 5mm	8mm

Both got lighter in the generation change. The Strike 2 by about 9% (19 ÷ 210), the Alphafly 4 by 5%.

Which is better for ease of running, comfort, speed and cushion?

Ease of running: it splits by where you land. The 5mm Strike 2 is straightforward for a run that lands midfoot to forefoot. The 8mm Alphafly 4 has a tilt that suits people who land toward the heel and roll forward.

Comfort: Strike 2. With standard laces you can change the tightness to your instep height and width. The Alphafly 4 has an Atomknit upper with no seams, tightened by a cable at the midfoot, and the wrapped feeling is stronger.

Speed: both are race-day shoes. The Strike 2 has a Helion HF made 15% lighter and a warped plate that got lighter and stiffer. The Alphafly 4 claims 10% more energy return than the previous generation. The aim of saving your legs for the end of the race is common to both.

Cushion: Alphafly 4. It stacks ZoomX LT, up to 17% lighter than ZoomX, above and below the plate, and rebuilds the Air Zoom to be softer and quieter than the previous generation. For someone who wants to soften landing impact over long distances, this one responds with more.

Who is it for?

Who the Cloudboom Strike 2 suits: People who land midfoot to forefoot. People who want to fine-tune tightness with laces. People who want a race-day shoe they can buy now for this autumn's full or half.
Who the Alphafly 4 suits: People used to shoes with a drop around 8mm. People who want to keep softness and return through the half and the late full. People who were bothered by the stiffness or noise of the previous Alphafly.

If you are switching from a shoe with a different drop, it is safer to get used to that tilt in training once before using it on race day. The table lining up each maker's race shoes is in the carbon thick-sole comparison article.

Price and where to buy

Official prices are each maker's Japan official listing of Oct 18, 2026 (tax included; the Vaporfly 4 is the Oct 13 listing). The Rakuten range is what shops showed on the day I checked.
Model	Official price	Rakuten price range
Cloudboom Strike 2	JPY 35,200	—
Alphafly 4	JPY 39,600 (coming soon)	—
Vaporfly 4 (Nike's sibling)	JPY 29,700	JPY 23,980–31,000

The Strike 2 is already in stores. Some Rakuten shops still carry the original Strike, so choose after checking the "2" in the product name.

The Alphafly 4's wide release is Oct 29 in the global announcement, but no Japan date is out yet. If you have a race coming, add it to your plans after you see the release date.

Nike Alphafly 4

Before release: available from Oct 29

FAQ

Which is better for a full marathon, the Cloudboom Strike 2 or Alphafly 4?

Both are shoes for the full and half, and it comes down to how you run, not which is better. The Alphafly 4 if you land toward the heel and want softness late too; the Strike 2 if you land on the front and push with a low tilt. How On and Nike's other models divide is in the On shoe guide and the Nike shoe guide.

Do the Cloudboom Strike 2 and Alphafly 4 fit the same?

The Strike 2 is true to size. Unisex 22.0–31.5cm, one width. The forefoot is wide and the instep low.

For the Alphafly 4, choose by measured foot length, per Nike's size chart: if between two sizes, the larger. With a 25.0cm foot, I'd take 25.0cm in both the Strike 2 and Alphafly 4. Try on in the evening, when your feet swell, with your usual socks.

What are the siblings of the Alphafly 4 and Strike 2?

Below the Alphafly 4 is the Vaporfly 4, with a 6mm drop usable from 10km. The Strike 2 has the LightSpray version with a one-piece upper without laces, 33g lighter, and the Cloudboom Volt up to the half.

Gear in this article

Ads and images: Rakuten Ichiba

Nike Vaporfly 4

Sources

Pictured (Rakuten Ichiba): Nike Vaporfly 4Nike Alphafly 4 ReviewAbout 188g, JPY 39,600, and "coming soon" in Japan. The Nike Alphafly 4 is a max-cushion carbon shoe for runners who want softness and return left late in a full marathon. About 188g, 8mm drop, 5% lighter than the last generation, JPY 39,600. We also cover how it differs from the Alphafly 3 and Vaporfly 4, in numbers.Shoes and Gear, Oct 15, 2026

Products pictured (Rakuten Ichiba): ASICS METASPEED SKY TOKYO / ASICS METASPEED EDGE TOKYO / Nike Vaporfly 4 / adidas Adizero Adios Pro 410 max-cushion carbon marathon shoes compared by the official numbersStack heights are even; the difference is in the drop. Comparing 10 max-cushion carbon shoes by the official numbers, stack heights line up at 39–41mm, while drops range from 5 to 8mm. The lightest is the ASICS METASPEED RAY at about 129g. I also worked out where World Athletics' 40mm rule is measured, and the price per gram.Marathon · Oct 18, 2026

Pictured (Rakuten Ichiba): On Cloudsurfer Max / On Cloudsurfer / On Cloudrunner (check the generation in the product name) / On Cloudmonster Hyper (check the generation in the product name)Choose On Running Shoes by Sole ShapeOfficial numbers for 12 models, sorted by role. Choosing an On shoe comes down to type (role) and sole shape. My top pick for daily training is the Cloudsurfer 2 (261g), the Cloudsurfer Max for long distances, and the 191g Cloudboom Strike 2 for race day. I compare 12 models by weight, drop and price, and spell out the differences between siblings by the numbers.Shoes & gear · Oct 15, 2026

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Pictured (Rakuten Ichiba): ASICS GEL-KAYANO 33GEL-KAYANO 33 vs NOVABLAST 6Choose by weight, stack, stability and bounce. The GEL-KAYANO 33 and NOVABLAST 6 differ by 45g and in how they support you. The KAYANO, at 298g, controls foot wobble; the NOVABLAST, at 253g, has high energy return up front. I compare stack height, width and price in a table and say who each one suits.Shoes & gear · Oct 18, 2026

Cloudboom Strike 2 vs Alphafly 45mm and 8mm drop