When Jacob Kiplimo crossed the finish line in Lisbon on Sunday, he was wearing a shoe that doesn’t officially exist yet.
Photos posted by the Running Junkiesss Facebook group show Kiplimo holding up a pair of Nike Alphafly 4 prototypes with the words “57:20 WR” written across the soles in marker pen. Which is, honestly, a pretty good way to christen a pair of shoes. The shoe in question — known internally as the Nike Dev 164 — is the next generation of Nike’s flagship racing platform. It is not available to buy. There is no official release date. And it just helped set a half marathon world record.
What Is the Nike Dev 164?
The short version: it’s the Alphafly 4, before Nike is ready to call it that.
It’s a development prototype — still being tested and refined, not yet signed off for consumer release. But what’s circulating in photos online looks noticeably different from the Alphafly 3. The midsole is more aggressively sculpted, the upper is minimal to the point of looking almost translucent, and the whole thing has a rawer, more stripped-back feel than its predecessor.
As for legality — yes, the Dev 164 appeared on the official approved list as of February 2026, and is cleared for competition until 12 February 2027.
One catch worth knowing: it’s not approved for World Athletics Series events or the Olympics. Only road races, cross country, and mountain and trail races. The EDP Lisbon Half Marathon qualifies on all counts, so there’s no asterisk on the record. The shoe was legal, the record stands, move on.
He Didn’t Even Use It at Chicago
Here’s the part that makes Sunday’s shoe choice actually interesting.
At the 2025 Chicago Marathon — which Kiplimo won — he reportedly stuck with the Alphafly 3 while other elites were already field-testing the Dev 164. One of those testers was American runner Conner Mantz, who ran 2:04:43 in the prototype and broke the American marathon record in the process. Heads turned.
Kiplimo took the win in the older model and apparently thought about it for five months. Then he showed up in Lisbon, switched to the prototype, and ran faster than any man in recorded history over 13.1 miles.
Not a bad way to make up your mind.
What We Don’t Know (Most of It)
Nike hasn’t officially announced the Alphafly 4 or confirmed anything about a release timeline. Rumour sites and shoe trackers have pointed toward sometime in 2026, possibly around the spring marathon season, but nothing is confirmed. On price — the Alphafly 3 already isn’t cheap, and prototypes don’t tend to get more affordable on their way to retail shelves.
What it actually feels like to run in, how it compares to the Alphafly 3 for non-elite feet, and whether it’s worth the presumably eye-watering price tag — all completely unknown. Right now the Dev 164 has been on a handful of elite athletes’ feet and that’s about it. The rest is speculation.
