On Cloudboom Max
£220
UK RRP
Midsole to scale · mm · red dashes mark the 40mm road limit
- Weight
- 296 g
- men's US 9
- Stack
- 40 / 32 mm
- heel / forefoot · drawn above, against the 40mm line
- Drop
- 8 mm
- Plate
- nylon
- Foam
- Helion HF
- Stability
- stable and forgiving
- Competitive life
- ~650 km
- before the foam stops giving it back
- Built for
- Half · Marathon
Verdict
On’s long-run trainer, and the first of theirs with energy return worth the name. A big, protective shoe for time on feet.
■ Caution
At 296g it is one of the heaviest shoes here, and it is priced like a racer. Hard to justify against cheaper, lighter trainers.
Straight answers
- Is the On Cloudboom Max legal for road racing?
- Yes. The On Cloudboom Max measures exactly 40mm — precisely on the World Athletics 40mm road limit, legal with no margin. The limit only binds Applicable Competitions (championship, elite and record-eligible fields); most club and local races apply no shoe rule at all.
- How much does the On Cloudboom Max weigh?
- 296g in a men's US 9 (UK 8), by the manufacturer's stated figure. Weight moves roughly 3.5% per UK size step, so a UK 11 weighs materially more than the spec sheet says.
- What is the stack height and drop of the On Cloudboom Max?
- 40mm at the heel and 32mm at the forefoot — a 8mm drop. A nylon plate runs through Helion HF.
- How long does the On Cloudboom Max last?
- We estimate roughly 650km of competitive life — the point at which the foam has degraded enough that you are no longer getting the benefit you paid £220 for, not the point at which the shoe falls apart. Spread over race cycles, that is what the cost-per-race figure on this page is built from.
- Is the On Cloudboom Max good for a marathon?
- Yes — the marathon is one of the distances it is built for (half marathon and marathon). On’s long-run trainer, and the first of theirs with energy return worth the name. A big, protective shoe for time on feet.
Legality by event
Cloudboom Max at 40mm · every panel drawn to one scale
Road racing
40mm · 0.0 clear
Track events
20mm · 20.0 over
Field events
20mm · 20.0 over
Cross country (spiked shoes)
20mm · 20.0 over
Cross country (non-spiked)
40mm · 0.0 clear
Race walking
40mm · 0.0 clear
Mountain and trail
no limit
Drawn from the manufacturer’s stated stack height, which is not the measurement World Athletics takes — the rule is measured on a men’s US 8.5 sample, and larger sizes may legally exceed it. An indication, not a ruling. Limits bind Applicable Competitions; most club and local races apply no shoe rule at all. What that means in practice.
Reading — what would the Cloudboom Max save you?
Time bought back
−0:56 – 2:18
Off 3:45:00, that lands you at 3:42:42 on the optimistic end.
- Per race
- £21
- ~10.3 races in the foam
- Per second
- £0.22
- whole-life basis
- Sticker
- £220
- UK recommended retail
Economy gain 1.6–2.8% v. a traditional flat, adjusted for pace and your current shoes. Full method.
Manufacturer-stated specs unless marked estimated · last reviewed 2026-09-04 · prices are UK RRP; check the retailer for the live figure.