Just days before the 2025 Chicago Marathon, a mysterious new Nike shoe quietly appeared on the official World Athletics list of approved models. The listing, filed under the code Nike-Dev 16141, makes the shoe eligible for competition from October 2, 2025, through October 1, 2026, just in time for one of the biggest races of the year.
The “Dev” designation is Nike’s standard label for developmental prototypes used by elite athletes before a public release.
These coded shoes often precede major launches, giving Nike’s top runners a chance to test new innovations in real racing conditions. Both the Vaporfly and Alphafly series followed the same path, starting life as nameless prototypes before becoming two of the most influential running shoes ever made.
That’s why this new entry on the World Athletics list has sparked immediate speculation across the running world. It suggests that Nike is preparing to roll out the next evolution of its super shoe lineup, and Chicago could be its global debut.
The photo shared by the reliable prototype tracker @protosofthegram shows a silhouette that’s unmistakably within the Alphafly family, featuring an aggressive forefoot cavity, visible dual Air Zoom pods, and an even more sculpted midsole.
There’s no official confirmation from Nike yet, but the timing fits the brand’s established playbook. When a prototype appears on the World Athletics site right before a Nike-sponsored race, in this case the Chicago Marathon, it’s almost always a signal that something big is coming.
Historically, Nike uses these moments to give the world its first look at new technology on the feet of its fastest athletes. With names like Jacob Kiplimo and Conner Mantz expected on the start line, fans will be watching closely to see what’s laced up on race morning.
The World Athletics approval itself is more than a formality. Since 2020, all racing shoes used in sanctioned events must appear on the organization’s public list, ensuring compliance with regulations on sole thickness and plate design. When a model appears with a “Dev” tag, it means the shoe meets competition standards but isn’t yet for sale, a way for brands to test their innovations legally and transparently.
That distinction matters, especially given the sport’s history with technological controversy. When the first Alphafly prototypes appeared ahead of Eliud Kipchoge’s sub-two-hour marathon in Vienna, debates erupted over fairness and accessibility. This time, World Athletics’ clearer approval process ensures that any records set in Chicago, should they happen, will be legitimate.
For now, Nike isn’t saying whether the Nike-Dev 16141 will become the Alphafly 4, but few in the running world doubt it. The brand has always used the biggest stages to unveil its most important products, and few stages are bigger than Chicago in October. Whether the shoe appears at the expo or only on the feet of sponsored elites, its presence marks the beginning of a new chapter in Nike’s ongoing arms race for speed.
