On Cloudultra Pro 'Pearl / Lychee' (3MF30174107) — Competition Ultra-Trail Mountain Racing Shoe

What Is the On Cloudultra Pro ‘Pearl / Lychee’?

The On Cloudultra Pro ‘Pearl / Lychee’ (Style Code: 3MF30174107) is the highest-positioned shoe in today’s full lineup at $175 — and the only shoe in today’s range built for a category of running that most runners will never enter: ultra-trail mountain racing. The Cloudultra is On’s ultra-distance trail platform, designed for races measured not in kilometres but in mountain ranges — the 50-mile, 100-mile, and 100-plus-mile mountain events where the course ascends and descends the equivalent of multiple Everests over technical alpine terrain, where runners are on their feet for 20 to 40+ hours, and where a shoe failure at mile 60 means a race that ends not at the finish line but at the side of a mountain trail. The Pro designation marks this as the competition-grade specification of that platform: weight-reduced and performance-tuned beyond the standard Cloudultra for the runner who is not just completing the distance but racing it. The Pearl / Lychee colorway — iridescent pearl white and translucent lychee pink — is the Cloudultra Pro’s most quietly confident palette: the softest colors on On’s most technically demanding shoe, worn by the runner who needs no visual announcement of where they are going. US M7–M11 / W8.5–W12.5 / EU 40–45.

Quick Facts

• Brand: On Running (Zurich, Switzerland — est. 2010)
• Model: Cloudultra Pro — competition-grade ultra-distance trail racing shoe
• Style Code: 3MF30174107
• Colorway: Pearl / Lychee — iridescent pearl white + translucent lychee pink-white
• Outsole: Missiongrip™ — On’s ultra-trail rubber compound; grip on wet rock, loose dirt, mud, mixed alpine terrain
• Midsole: Trail-tuned Helion™ + trail CloudTec® + integrated rock plate
• Rock plate: Integrated midsole protection against sharp rocks and roots — ultra-trail essential
• Upper: Reinforced protective trail mesh — precision fit for ultra-distance blister prevention
• Specification: Pro — competition-grade; weight-reduced and performance-tuned beyond standard Cloudultra
• Gender: Men’s / Unisex sizing
• Sizing: US M7–M11 / W8.5–W12.5 / EU 40–45
• Price: $175
• Category: Ultra Trail / Mountain Racing / Competition / 50–100+ Mile Events
• Fit: Precision race fit — true to size; size up half if between sizes or for longer ultra distances where foot swelling is expected

Specs & Technologies

What Ultra-Trail Racing Actually Is — The Context the Cloudultra Pro Was Built For

Ultra-trail racing is a distinct category from trail running and from road ultra-marathons. The defining events — UTMB (Ultra-Trail du Mont-Blanc, 106 miles / 33,000 feet of elevation change through France, Italy, and Switzerland), Western States 100 (100 miles through the Sierra Nevada), Hardrock 100 (100 miles at altitude through the San Juan Mountains of Colorado) — share three characteristics that define the shoe requirements for completing or racing them. First, extreme terrain: technical alpine trails with loose rock, wet rock, exposed roots, mud, snow, and talus fields where traction failure is a safety risk, not just a performance one. Second, extreme duration: elite runners complete these courses in 16–24 hours; the average finisher takes 28–40 hours, meaning two nights of running and one full day of continuous movement. Third, extreme elevation: UTMB’s 33,000 feet of cumulative elevation gain is the equivalent of ascending Everest from sea level more than three times. Each of these characteristics generates a specific shoe requirement: extreme terrain demands traction on surfaces that road shoes and hybrid trail shoes cannot manage; extreme duration demands cushioning that does not fatigue over 30+ hours of use and a fit that does not generate blisters over the same period; extreme elevation demands a rock plate that allows the foot to land on technical surfaces without the pain that makes running impossible. The Cloudultra Pro is built to address all three simultaneously.

Missiongrip™ — On’s Ultra-Trail Rubber Compound

Missiongrip™ is On’s most advanced trail outsole compound, developed specifically for the traction demands of ultra-trail mountain racing rather than for the mixed-surface demands of hybrid trail running (which use the standard Contagrip-class hybrid compounds). The distinction matters: hybrid trail outsoles are designed to perform adequately on both trail and road, which means their traction compound is a compromise — trail-capable but road-compatible. Missiongrip™ makes no such compromise. It is formulated exclusively for off-road traction, with a rubber compound that prioritises grip on the surfaces that define ultra-trail racing: wet rock (where the rubber’s Shore hardness and texture must balance friction against skating); loose dirt and scree (where the lug depth and spacing must channel debris away from the contact surface rather than packing it in); mud (where lug shape must allow self-cleaning under load); and the variable surface transitions that define mountain racing (where grip cannot be adjusted between surfaces — the shoe must handle whatever the trail presents in the next step). The lug pattern is directional: shaped and angled for the specific force directions of mountain racing — braking on technical descents, power transfer on steep ascents, lateral stability on off-camber traverses.

The Rock Plate — Why Ultra-Trail Shoes Need Underfoot Protection

The rock plate is the component that most directly separates ultra-trail shoes from every other category in today’s lineup. It is a semi-rigid protective layer integrated into the midsole, positioned between the CloudTec® pods above and the Missiongrip™ outsole below, whose function is to distribute point loads across the full midsole footprint rather than allowing them to concentrate at the single contact point. On technical alpine terrain — talus fields, rocky ridgelines, stream crossings with submerged rocks — the foot lands on surfaces that include sharp edges, protruding roots, and angular rocks whose contact area may be less than a square centimetre. Without a rock plate, a running footstrike on such a surface transmits the full landing force through that single point directly into the foot’s soft tissue — a sensation ranging from painful to injury-causing, and one that forces the runner to place every step with deliberate care rather than running freely. The rock plate distributes this load across the plate’s full area, converting a point load into a distributed load that the foot’s plantar surface can absorb without pain or injury. Over 50 to 100 miles of technical terrain, the rock plate’s protection allows the runner to maintain running gait on surfaces where an unprotected shoe would force hiking — a difference measured in hours of race time and in the physical condition of the foot at the finish.

Trail-Tuned Helion™ — Cushioning for Ultra Distance

The Cloudultra Pro’s Helion™ formulation is distinct from the road versions used in the Cloudsurfer and Cloudstratus. Road running cushioning is optimised for the explosive, high-frequency impact of pavement running — a runner covering a 10K at race pace takes approximately 8,000–10,000 steps, each at relatively high force and frequency. Ultra-trail running presents a different cushioning demand: a runner covering 100 miles takes approximately 160,000–200,000 steps, at generally lower individual impact force (mountain terrain moderates pace and therefore impact) but over a duration where cushioning fatigue — the progressive reduction in foam responsiveness as the foam’s cell structure fatigues under repeated compression — is a primary concern. The trail-tuned Helion™ is formulated for this demand: not for peak explosive response but for consistent protection across extreme duration — a foam whose cushioning properties at mile 90 are as close as possible to its properties at mile 1.

‘Pearl’ — The Iridescent White of Formed-Under-Pressure

Pearl is the iridescent white produced inside a mollusc shell when an irritant is coated in layers of nacre — calcium carbonate crystallised in aragonite form and deposited in concentric layers over months or years, each layer thin enough to produce structural colour interference, the phenomenon where light reflected from adjacent layers of different refractive indices interferes constructively and destructively at different wavelengths to produce the characteristic shimmer of pearl. Pearl is not a single colour: it is an interference pattern that produces different apparent colours as the viewing angle changes, shifting between white, cream, pink, blue, and green depending on the light and the angle of observation. As a colour name, Pearl carries this: it is the white that is not quite white, that has depth and the faint iridescence of the organic material it is named for. On the Cloudultra Pro, Pearl describes an upper that carries the visual quality of something formed under pressure over time — which is precisely what the runner who wears it has done.

‘Lychee’ — The Translucent Pink of Concentrated Sweetness

Lychee is named for the flesh of the lychee fruit — the translucent, pale pink-white of the fruit’s interior when the rough red shell is removed, a colour that is simultaneously delicate in its pinkness and intense in its translucency, a pink that seems lit from within because the fruit’s flesh is thin enough to transmit light rather than simply reflect it. Lychee as a colour is not the saturated pink of a statement palette: it is pale enough to read as nearly white in certain lights and as a definite soft pink in others, an accent colour that adds warmth and delicacy without committing to the visual assertiveness of saturated pink. On the Cloudultra Pro, Lychee provides the warmth that Pearl alone would lack — the soft pink accent that gives the Pearl base its femininity without overwhelming it. The two colours together produce the Cloudultra Pro’s defining palette quality: softness as a strength rather than softness as an absence of strength.

The Pro Specification — What Competition-Grade Means

The Pro designation marks the Cloudultra Pro as distinct from the standard Cloudultra in two specific dimensions: weight and tuning. Weight reduction in competition footwear is not comfort reduction — it is the systematic removal of every gram that does not contribute directly to performance or protection. In the Cloudultra Pro, this means upper materials that are lighter without being less protective, midsole geometry that is optimised for efficiency rather than for the training-use durability margin that adds weight to standard versions, and construction details that are simplified or eliminated where they serve training use rather than competition use. The tuning difference is subtler: the Pro’s components are calibrated for the specific output ranges of competition running — the pace, cadence, and foot-strike patterns of a runner who is racing rather than completing — rather than for the wider range of intensities that training use requires. At $175, the Cloudultra Pro is today’s highest-priced shoe — $6 above the next tier (Salomon x MM6 XT-4 Mule and Salomon XT-Whisper Void at $169) — with its premium earned by the Pro specification’s technical completeness: Missiongrip™, rock plate, trail Helion™, trail CloudTec®, and Pro weight reduction, all in a single shoe built for the most technically demanding running context in today’s full lineup.

Cloudultra Pro vs. Cloudsurfer Trail 2 WP — On’s Two Trail Shoes Today

Decision rule: if your goal is completing or racing ultra-trail mountain events on technical alpine terrain — Cloudultra Pro. If your goal is daily training that transitions between road and trail, with all-weather protection — Cloudsurfer Trail 2 WP.

Sizing — Men’s / Women’s / EU Conversion Table

The On Cloudultra Pro is sold in men’s / unisex sizing. Women typically size up approximately 1.5 sizes from their women’s US size (e.g., women’s US 7 → men’s US 8.5 / EU 42). For ultra-distance events, consider sizing up half a size from true size to accommodate the foot swelling that occurs over 20–40 hours of running.

Who Is the On Cloudultra Pro ‘Pearl / Lychee’ For?

Three profiles: the ultra-trail racer who competes in or trains specifically for 50–100+ mile mountain events — the runner for whom the Cloudultra Pro’s Missiongrip™ outsole, integrated rock plate, trail-tuned Helion™ ultra-duration cushioning, precision race fit, and Pro weight reduction represent the complete technical specification for the most demanding running context today’s lineup addresses, at $175 as today’s highest-positioned shoe earning its price through technical completeness; the Pearl / Lychee palette buyer who wants the Cloudultra Pro’s most quietly confident colorway — iridescent pearl white and translucent lychee pink on On’s most technically demanding shoe, the softest palette on the hardest purpose, worn by the runner who understands that the mountain does not care what colour the shoes are; and the serious trail runner who wants On’s most fully developed trail technology stack — Missiongrip™ compound, rock plate protection, trail CloudTec® debris resistance, and competition-grade weight reduction — available in today’s lineup at the ceiling price that the full technical specification justifies.

Frequently Asked Questions

Q: What is the style code?
A: 3MF30174107.

Q: What is the difference between the Cloudultra Pro and the standard Cloudultra?
A: The Pro specification adds two things: (1) weight reduction — systematic removal of every gram that does not contribute directly to performance or protection; (2) competition tuning — components calibrated for the pace, cadence, and foot-strike patterns of racing rather than the wider range of training use. The standard Cloudultra is built for training durability; the Pro is built for race-day performance.

Q: What is Missiongrip™ and how does it differ from standard trail outsoles?
A: Missiongrip™ is On’s ultra-trail-specific rubber compound, formulated exclusively for off-road traction — wet rock, loose dirt, mud, and mixed alpine terrain. Unlike hybrid trail outsoles (which balance trail and road performance), Missiongrip™ makes no road performance compromise: it is optimised purely for the traction demands of mountain racing. The directional lug pattern is shaped for braking on descents, power transfer on ascents, and lateral stability on off-camber terrain.

Q: Why does the Cloudultra Pro have a rock plate when most running shoes do not?
A: On technical alpine terrain, the foot lands on surfaces with sharp rocks and protruding roots whose contact area may be less than a square centimetre. Without a rock plate, landing force concentrates at that point, causing pain that forces cautious stepping rather than running. The rock plate distributes point loads across the full midsole, allowing the runner to maintain running gait on technical surfaces where an unprotected shoe would force hiking.

Q: Why doesn’t the Cloudultra Pro have waterproofing when the Cloudsurfer Trail 2 does?
A: Ultra-trail racing prioritises ventilation over waterproofing. Over 20–40 hours of running, foot perspiration at racing intensity generates significant heat and moisture; a waterproof membrane, even a breathable one, reduces ventilation compared to an unlined mesh. At ultra-distance racing intensities, the heat reduction from an unlined mesh is more important than water exclusion — racers manage wet crossings by accepting temporary saturation and relying on drainage and ventilation to dry the shoe in motion.

Q: Should I size up for ultra distances?
A: Possibly. Foot swelling over 20–40 hours of running is real and can amount to half a size or more. If you are between sizes, size up. If you are competing in events over 50 miles, consider a half-size up from your true road running size. The precision race fit is designed to prevent movement and blister formation — some extra room accommodates swelling without creating movement.

Q: How does women’s sizing work?
A: Women size up approximately 1.5 sizes from their women’s US size (e.g., women’s US 7 → men’s US 8.5). Same On Running convention as all other On shoes in today’s lineup.