What Exactly Is On’s Spray‑On Marathon Shoe?
On’s latest experiment in marathon tech looks more like sci‑fi than sportswear. Instead of stitching together dozens of fabric pieces, the Swiss brand uses a LightSpray robot to spray a single‑filament polymer over a shoe last, building an ultra‑light, stretchy mesh upper in roughly three minutes per shoe. The result is a laceless, sock‑like shell bonded to a carbon‑powered racing platform, first seen on prototypes worn by Hellen Obiri before becoming the Cloudboom Strike, On’s fastest‑ever distance shoe. The same process now also powers the Cloudmonster 3 Hyper for high‑end training. By condensing about 200 conventional assembly steps into one robotic motion, LightSpray promises big gains in precision, weight reduction and waste minimisation. Around the London Marathon, On has brought the LightSpray robot to a Hanover Square pop‑up, letting runners watch the ‘Spiderman’ upper being created and try the finished sneakers on foot.
How LightSpray Compares With Today’s Carbon Super Shoes
Modern marathon super shoes, from On’s Cloudboom Strike to rivals such as Adidas’ Adizero Adios Pro EVO 3, rely on tall stacks of responsive foam and stiff carbon structures to boost energy return. Adidas, for example, uses a carbon ENERGYRIM between dual foams and extremely lightweight uppers inspired by kitesurfing sails in the Adios Pro EVO 3, chasing maximum speed with minimal grams. LightSpray targets the same performance problem from a different angle: radically simplifying how the upper is built. Instead of panels and overlays, the robot sprays a web‑like mesh exactly where support, stretch or lockdown is needed. Underfoot, LightSpray shoes still look like familiar plated racers; the revolution is above the midsole. In theory, spraying on the upper trims even more weight and can fine‑tune fit around each foot, something traditional, mass‑produced uppers struggle to match at scale.
Could You Actually Race a Marathon in Spray‑On Shoes?
For elite athletes, LightSpray has already been battle‑tested. On points to major marathon wins and Ironman victories in the Cloudboom Strike as proof that the sprayed‑on upper can survive 42km of hard racing. The promised benefits are obvious: a precise, glove‑like fit with no laces to fiddle with, less material weight, and targeted support zones to reduce hotspots or pressure points. The big question is practicality for the wider marathon field. Transition time at the start is minimal – the shoe is sprayed in the factory, not on your foot – so race‑morning logistics look similar to current super shoes. Durability, however, is likely closer to existing top‑end racers, which are typically optimised for performance over longevity rather than hundreds of training kilometres. Comfort over four or five hours will depend on how forgiving that finely tuned mesh feels once the early‑race adrenaline fades.
Regulations, Real‑World Pros and Cons, and Malaysian Access
From a rules perspective, LightSpray shoes remain conventional enough: there is still a physical upper, a midsole with embedded plate, and no visible attempt to bypass stack‑height limits, so they are more an evolution of marathon super shoes than a new category. The pros are clear: less waste in production, rapid manufacturing, and the potential for more personalised fit. Drawbacks include limited durability and likely premium pricing, similar to how the Adidas Adizero Adios Pro EVO 3 sits at the very top of the market and targets 2:30–3:00 marathoners rather than hobbyists. In Malaysia, On already sells performance shoes through selected retailers and online channels, so LightSpray models will probably arrive first in very limited drops, realistically aimed at competitive runners chasing big personal bests. For most marathoners, they will be an aspirational option rather than a daily‑training workhorse.
After Carbon: Is On‑the‑Spot Footwear the Next Wave?
On’s London Marathon tech showcase hints at a broader future where shoes are partially made or customised on demand. LightSpray already compresses traditional upper manufacturing into a single robotic step, and On is scaling the concept via a dedicated factory in Busan that it describes as a ‘robot farm’. As production ramps up and more ‘farms’ come online, it is easy to imagine race‑expo stations or flagship stores where uppers are sprayed or midsoles are 3D‑printed based on your gait, weight and pace targets. For Malaysian runners, that could eventually mean ordering a marathon shoe tuned to Kuala Lumpur heat, Putrajaya roads or Penang bridge conditions rather than settling for a generic fit. Carbon plates and maximal foam will remain central, but the next competitive edge may come from how precisely brands can build the shoe around each individual foot.
