Men's Cloudboom Max
ON

Men's Cloudboom Max

Max cushioning and a glass fibre Speedboard — the shoe for the marathon build, not just the race

$129.99
Color: Honeydew/Lilac
Also inWomen's
Size:
Size guide
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Top features
Double-layer Helion HF hyper foam
Glass fibre-infused Speedboard
CloudTec cushioning
Description

ON's marathon-training shoe — a double layer of Helion HF hyper foam over a glass fibre Speedboard, built for long fast miles.

Perfect for
Long runs
Marathon training blocks.
Half and full marathon
Cushion over outright speed.
Heavy mileage weeks
Where a glass plate beats carbon.
Features
  • Double-layer Helion HF hyper foam. Two layers of ON's highest-return foam rather than one. It is where the energy return comes from, and why the shoe still feels alive deep into a long run instead of going flat at mile 15.
  • Glass fibre-infused Speedboard. A full-length plate for efficiency and support. Glass fibre rather than carbon — more forgiving underfoot and more durable over high mileage, which is exactly why this works as a training shoe rather than a race-day-only one.
  • CloudTec cushioning. ON's signature Clouds, tuned here for fast runs rather than easy ones. They compress on landing and lock out for toe-off, which is what stops a max-cushion shoe feeling vague.
  • Padded heel, moulding upper. A padded heel built for comfort over long distances, under a lightweight breathable mesh upper ON describe as moulding and adjusting to your foot's movements as you run.
  • Made for marathon training. ON's own words. They rate it max cushioning and stable support, and label it for the half and the full — this is the shoe built for the volume that leads up to a race, not just the race itself.
Size & Fit
Narrow
Regular
Roomy

Standard medium width. Fits most feet true to size.

  • Men's US 7–14. One width, standard lacing.
  • ON state it plainly: regular fit, true to size. Take your usual running-shoe number.
  • The mesh upper moulds and adjusts to the foot as you run, so it settles in over the first few runs rather than needing breaking in.
  • Between sizes and planning to run long? Feet swell over a marathon — the larger size is the safer bet.
  • ON rate the support Stable rather than neutral. There is no medial post, but the wide padded platform makes it feel more planted than a neutral shoe of the same stack.
Open size guide
Materials
  • Knock off loose dirt after each run with a soft brush or dry cloth.
  • Remove the insoles and laces before any deeper cleaning. Hand wash with mild soap and cool water — never machine wash or tumble dry.
  • Air dry at room temperature away from direct heat; stuffing with paper helps hold the shape.
  • Never leave them in a hot car. Heat is the fastest way to flatten a max-cushion midsole permanently.
About the brand

On was born in the Swiss Alps with one mission: revolutionize the running sensation. Their CloudTec® cushioning gives every stride a soft landing and powerful takeoff. At Mountain Sports, we love On because it blends sleek design with performance innovation — gear that makes every run feel lighter.

Shop all ON

SKU 3MF30314325 · Style 3MF3031
Size guide

On Size Chart - Men's Footwear

On Sizing Chart

Conversions between US, UK, Europe, Japan (cm) and Brazil sizes as published by On. On footwear fits true to size.

Men's Footwear Size Conversions:

US UK EU JP (CM) BR
7 6.5 40 25 37
7.5 7 40.5 25.5 38
8 7.5 41 26 39
8.5 8 42 26.5 N/A
9 8.5 42.5 27 40
9.5 9 43 27.5 41
10 9.5 44 28 N/A
10.5 10 44.5 28.5 42
11 10.5 45 29 N/A
11.5 11 46 29.5 43
12 11.5 47 30 44
12.5 12 47.5 30.5 45
13 12.5 48 31 46
13.5 13 48.5 31.5 47
14 13.5 49 31.5 N/A
15 14.5 50 33 47

To find your size, measure your foot from heel to longest toe in centimeters and match it to the JP (CM) column. If you're between sizes, choose the larger size for a roomier fit.
Performance

How it ranks across conditions.

Calibrated against comparable products we stock, so you can compare like for like.

Cushioning

Firm
Moderate
Plush
Max

ON rate the cushioning 5 out of 5 — their maximum. A double layer of Helion HF hyper foam under the CloudTec system, built to stay comfortable deep into a long run.

Stability

Neutral
Light support
Structured

ON call the support Stable rather than neutral, and rate stability 4 out of 5. There is no medial post here — the steadiness comes from a wide, padded platform and a Speedboard that resists twisting. If you are used to genuinely neutral shoes, expect this to feel more planted.

Traction

Low
Moderate
Aggressive

A rubber outsole for grip on the road. Dependable on wet pavement, and not intended for anything looser than a gravel path.

Responsiveness

Relaxed
Balanced
Springy

A double layer of hyper foam over a glass fibre Speedboard, which ON rate 4 out of 5. Springy — but the plate is glass fibre rather than carbon, so this is a shoe to train for a marathon in rather than to race one in.

Best for

Is this right for you?

Marathon training blocks

ON's stated purpose, and the thing it does best. Max cushioning for the long runs, enough plate to keep the pace honest, and a glass-fibre Speedboard that takes the weekly volume a carbon plate would resent.

Not for: At 296 g it is not a light shoe. If your session calls for turnover rather than distance, something leaner will serve you better.

Half and full marathon

ON label it a race shoe for the half and the full, and for a lot of runners that is the right call — a stable, deeply cushioned plated shoe is more use over four hours than a stiff racer you cannot hold form in.

Not for: A glass-fibre plate is a different proposition to carbon. If you are chasing a time and want maximum return per stride, this is not that shoe.

Heavy mileage weeks

This is where the glass fibre earns its place. It gives you plate efficiency on days when a carbon shoe would be overkill, and it lasts — so you are not spending race-shoe money on training miles.

Not for: Still a specialist. If you want one shoe for every run at every pace, the Cloud 6 is the more sensible everyday choice. Everyday option: Cloud 6

Full spec sheet

Technical Specs

Weight296 g
Heel-to-toe drop8 mm
CushioningMax — 5 of 5 by ON's own rating
MidsoleCloudTec with a double layer of Helion HF hyper foam
PlateGlass fibre-infused Speedboard — not carbon
UpperLightweight breathable mesh, padded heel
SupportStable — ON's own rating, 4 of 5. No medial post.
SurfaceRoad — running and road racing
SizesUS 7–14, standard lacing, one width — regular fit, true to size
Questions, answered

Before you buy.

Pulled from chats, emails and store visits. The things people actually ask us before they buy. Don't see yours?

Ask a question
Does it fit true to size?

Yes — ON state it plainly: regular fit, true to size. Take your usual running-shoe number. The upper is a lightweight mesh that ON describe as moulding and adjusting to the foot, so it settles in over the first few runs rather than needing to be broken in. Standard lacing, one width. If you are between sizes and plan to run long in these, the usual advice applies: feet swell over a marathon, so the larger size is the safer bet.

Is this a carbon-plated racer?

No, and the difference matters. The Cloudboom Max uses a glass fibre-infused Speedboard rather than a carbon plate. Glass fibre is more forgiving and considerably more durable, which changes what the shoe is for: ON describe it as made for marathon training rather than as their race-day flagship. In practice that means you get plate-assisted efficiency on long runs without spending a carbon racer's limited life on training miles — but you also do not get the snap of a true super-shoe. If a carbon racer is what you are after, that is a different shoe entirely.

ON say "Stable" — is this a stability shoe?

Not in the traditional sense, but it is not neutral either — ON rate the support Stable and score stability 4 out of 5. There is no medial post and no guidance rail. The steadiness comes from the shape: a wide, padded platform and a full-length Speedboard that resists twisting underfoot. So if you have been told you need a stability shoe for overpronation, this is not a substitute for one. But if you find tall max-cushion shoes wobbly and have avoided them for that reason, this is the one to try — it feels notably more planted than a neutral shoe of the same stack.

Can I train in it daily, or save it for long runs?

You can train in it far more freely than in a carbon racer — that is the whole point of the glass fibre plate. Carbon plates and the ultralight foams that go with them wear out fast, which is why racers get saved for race day. Glass fibre and a double Helion HF midsole take repeated mileage much better. That said, at 296 g this is a substantial shoe, and most people get on best using it for long runs and steady efforts while keeping something lighter for short easy days. Rotating two pairs extends the life of both.

How does it compare to the Cloudmonster or the Cloud 6?

Think of it as the top of ON's cushioned road range with a plate added. The Cloud 6 is the everyday shoe — lighter, simpler, the one to put ordinary miles through. The Cloudmonster is the big cushioned trainer without the plated, race-oriented geometry. The Cloudboom Max sits above both: maximum cushioning by ON's own rating, a glass fibre Speedboard for efficiency, and a road running style ON label Fast. It is the shoe for the long runs and race-pace efforts in a marathon build, not the one for a recovery jog.

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