Comparing 10 Carbon Thick-Sole Marathon Shoes by Official NumbersStack is flat, drop is where they differ

Comparing 10 carbon thick-sole shoes by official numbers, stack is flat at 39-41mm while drop spreads from 5 to 8mm. The lightest is the ASICS Metaspeed Ray at about 129g. World Athletics' rule caps road soles at 40mm, measured at just 2 points, 12% and 75% of the inside length.

What the "40mm rule" for thick soles actually measures on the shoe

Carbon shoe comparisons usually start from "40mm." But line up 10 pairs and the difference shows up in drop, not stack.

So where on the shoe is that 40mm measured? Open the World Athletics shoe regulations (the international governing body of athletics) and the answer comes down to just 2 points.

The rules even say thickness outside these 2 points "is not relevant to the requirements." Slight extra sole thickness in sizes above the reference does not count either. In other words, the "heel ◯mm" on each brand's official page is not necessarily the same as the position the rule measures.

One more point, on who it applies to. The rules apply as written to races run under World Athletics rules. The FAQ explains that club, school and masters-level races may set different rules. How a community marathon treats it is written in the entry guide of the race you enter.

Comparing 11 carbon thick-sole shoes by official numbers

From here, the shoe numbers. I opened the makers' official pages on Oct 13, 2026 and lined up weight, drop (the difference in sole thickness between heel and forefoot) and price, with the stack written below the table. Prices are what the official page showed that day (tax included).

Lined up, 3 things stand out.

First, stack (heel). PUMA is 40mm, adidas 39mm, the Rocket X 3 41mm. The 3 ASICS have a "maximum sole thickness" of about 39.5mm. All sit between 39mm and 41mm, a 2mm spread. Every maker builds just under the rule's cap. HOKA writes "heel 41mm" for the Rocket X 3, but that is HOKA's own figure.

Second, weights are hard to compare on equal terms. ASICS, PUMA and adidas are 27cm weights; Nike and the HOKA Rocket X 3 are 28cm weights. Shoes get heavier as size goes up, so the gap between the Vaporfly 4 at about 190g in 28cm and the Adios Pro 4 at 200g in 27cm is on the larger side of the 10g in the table.

Third, drop spreads 3mm, from 5mm to 8mm. That is larger than the stack gap (2mm). And drop is less affected by size conditions. Across makers, only drop and price could be compared as they are among the 10 pairs.

On Oct 17, I added the Brooks Hyperion Elite 6, released Sept 4, to the table. It is 192g in 27cm with a 7mm drop, 1g from the On Strike 2. But JPY 49,500 is the highest price in the table. How it differs from the previous generation is in the Elite 6 article.

Working out the weight difference: price per 1g and 42.195km

Price per gram

For the 8 pairs with weights, I divided the official price by weight. It is a guide to how much you pay for lightness.

The Metaspeed Ray is about JPY 256 per 1g, about 1.9 times the Rocket X 3 (about JPY 136) (256 ÷ 136). The lighter the shoe, the pricier each gram. The PUMA Elite 4 is 170g at about JPY 175, on the cheaper side per gram for its weight.

The Skechers Aero Elite, released Oct 2, is about 167g in 27cm at JPY 36,190, about JPY 217 per 1g (36,190 ÷ 167). The stack is 40/36mm with a 4mm drop, a plated shoe stacked right up to the 40mm cap.

How much does the weight difference add up over 42.195km?

The gap between the lightest, the Ray (about 129g), and the heaviest, the Rocket X 3 (226g), is 97g per foot (226 − 129).

Assume a stride of 1.2m, and 42.195km is about 35,163 steps (42,195 ÷ 1.2). Each step lifts 1 foot once, so the 97g difference repeats 35,163 times.

97g × 35,163 steps = about 3,411kg. By the finish, the total weight lifted by the feet differs by about 3.4 tons. With a 1.0m stride it is 42,195 steps and about 4.1 tons; at 1.4m, about 30,139 steps and about 2.9 tons. The shorter your stride, the more the lightness difference piles up. The size conditions differ between 27.0cm and 28cm, so read the gap as a guide.

Sky and Edge stack the same material upside down

The ASICS Sky Tokyo and Edge Tokyo share the same price, maximum stack and drop. You cannot tell them apart by the table's numbers. The difference is in how the sole is built inside.

FF LEAP is described as the lightest, highest-rebound foam in ASICS' lineup. The Sky puts it on the side closer to the ground, the Edge on the side closer to the foot. The Sky is arranged to aim at stability on landing, the Edge at limiting sinking from midfoot to heel.

Choosing is simple. If your stride lengthens as you speed up, the Sky; if your turnover rises, the Edge. If you cannot tell which you are, check on your watch's record whether cadence (steps per minute) rises along with pace.

The third, the Ray, is a different shoe. The whole sole is FF LEAP, about 129g. It is for elite runners who land on the forefoot.

Vaporfly and Alphafly: only one has an official page

On Nike Japan's official site, the product page that opened was the Vaporfly 4. Its use is "10K to the marathon." It changed 3 things from the Vaporfly 3: lighter upper, midsole and outsole, a larger angle for the carbon plate (Flyplate), and a drop reduced to 6mm.

The Alphafly is in the middle of a generation change. The Alphafly 3 product page shows "not available for purchase." In the search list, the Alphafly 4 appeared as "coming soon." Its product page does not open yet.

What decides it right now is the price gap. The Alphafly 4 is about 33% higher than the Vaporfly 4 (9,900 ÷ 29,700). Whether that premium is worth it can wait until the Alphafly 4's weight and build appear officially.

For anyone who wants to choose by numbers now, the Vaporfly 4, about 190g with a 6mm drop, is the easier pick.

Choose carbon thick-sole shoes by drop: who should pick which

Conditions first. I matched on 3: (1) a drop close to your current training shoe, (2) a full set of official numbers, (3) price per gram.

Want a first pair and want to check every number before buying: adidas Adios Pro 4

Weight, size condition, heel and forefoot stack, drop. The Adios Pro 4 has all 4 on its Japan official product page. At 39mm stack it has 1mm of room under the cap, a 6mm drop in the middle of the 10 pairs, and the lowest price of the 10. The plate is not 1 sheet but a row of carbon rods (ENERGYRODS 2.0).

The point to watch is weight. It is 200g in 27cm, 30g heavier than the PUMA Elite 4 (200 − 170).

Used to a training shoe with a large drop: PUMA Elite 4

If your usual shoe has a drop around 8mm, the PUMA Elite 4 is the closest. At about 170g it is the 2nd lightest of the 8 in the table. Among the 5 pairs under 200g, its official price ties the Vaporfly 4 for the lowest.

The point to watch is that the stack is written as exactly 40mm. On the official numbers, the room under the cap is 0mm. Also, its guide lifespan is 400km. If you will train in it too, splitting it from the 800km shoe in the article comparing 5 PUMA models fits the numbers.

Want lightness above all: Metaspeed Ray

About 129g is 41g lighter than the 2nd-lightest Elite 4 (170 − 129). That is 82g across both feet. With the same 1.2m stride as above, over 42.195km that is a gap of about 1.4 tons (41 × 35,163).

Who should skip it is clear too. It is aimed at "elite runners who run on the forefoot." Heel strikers and those buying their first carbon thick-sole shoe fall outside the official intent. Its price per 1g is also far above the other 8.

Like a small drop: On or ASICS

A 5mm drop is the On Cloudboom Strike 2 and the 3 ASICS. On's official weight is 191g, in the marathon and half marathon category. It has a plate blended with carbon (Speedboard).

The weak point is that its price runs above the Sky and Edge. The version with the same sole minus laces is 158g, 33g lighter (the LightSpray Cloudboom Strike 2 article). Other On models are lined up in the article on On shoes.

Want stack even if it is heavy: Rocket X 3

The HOKA Rocket X 3 has a forefoot stack of 34mm, thicker than the Adios Pro 4's 33mm and PUMA's 32mm. Its price per 1g is the lowest of the 8.

Two points to watch. 226g (28cm) is the heaviest of the 8. And if you enter a race aiming for a certified record, do not judge by the "heel 41mm" figure alone. World Athletics publishes a list of approved shoes. If a record is involved, checking the model number there is the sure way.

Who is it for?

The PUMA Elite 4's guide lifespan is 400km. At 30km a week, you reach it in about 13 weeks (400 ÷ 30). If you plan to do most of your training in this kind of shoe, the price per km comes to about JPY 74 (29,700 ÷ 400). It is a tool for people who can decide to wear it only on race day and a few times before.

FAQ

Which carbon thick-sole shoe should a beginner pick first?

Decide by target time. For a first pair for a sub-4 runner, the ASICS Magic Speed 5 (196g, carbon plate) is a candidate. Choosing by target time is covered in the article on shoes by target time.

Does the 40mm thick-sole rule apply to community marathons too?

It depends on the race, set in the competition rules field of the entry guide. World Athletics' FAQ explains that races at club or masters level may set different rules. For the half, the Sendai International and Kagawa Marugame guides have a 40mm limit (article on half marathon cutoffs and pace).

What drop is most common among carbon thick-sole shoes?

In these 10 pairs, 5 to 8mm. The 3 ASICS and the On are 5mm; PUMA and New Balance are 8mm. Choosing the number closest to your current training shoe keeps the foot angle from changing much.

Do trail running shoes have a 40mm cap too?

No. In World Athletics' thickness table, mountain and trail races have "no thickness limit." 40mm is the road figure and 20mm the track figure.

Can the PUMA x HYROX Elite 4 be used for marathons?

Stack, plate and drop are the same as the standard version. The difference is weight: the HYROX version is about 194g, the standard about 170g. It is 24g heavier, with a guide lifespan 100km longer. Use the standard version for marathons only, the HYROX version if you will use it for HYROX too. Detailed numbers are in the article comparing 5 PUMA models.

Gear in this article

Ads and images: Rakuten Ichiba

ASICS METASPEED SKY TOKYOASICS METASPEED EDGE TOKYONike Vaporfly 4adidas Adizero Adios Pro 4PUMA Deviate Nitro Elite 4ASICS METASPEED RAYOn Cloudboom Strike 2HOKA Rocket X 3

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