Adizero Prime X 2 vs Dragonfly 2

With 50mm under the heel, the Adizero Prime X 2 sits a full 10mm over the World Athletics limit for road racing, so no record or championship result run in it will stand. adidas built it that way on purpose, as a carbon-plated experiment in how far stack can go, and most reviewers ended up treating it as a very expensive super trainer rather than a racer. The softness won nearly all of them over. The weight was a different story: it put on a lot over the first Prime X, and several testers struggled to hold faster paces in it. Lab testing and two of the reviews rate it well for long runs and marathon-pace sessions, while one US panel called it a step backwards and preferred version 1. Coach's UK review lands in the middle, calling it great fun but priced above legal racers that do the job better. If you want an adidas marathon shoe for race day, the Adios Pro 5 is lighter, cheaper and legal. We'd buy the Prime X 2 for how it feels on long miles, and only once the price has dropped.

The Nike Dragonfly 2 is a distance track spike, built for the 1500m up to the 10,000m rather than the flat-out sprints. Underfoot you get a slab of ZoomX foam paired with a Pebax propulsion plate, so it feels far closer to a super racing shoe than the bare, punishing spikes of a decade ago. That is the whole idea. You keep the light, locked-in, aggressive feel of a track spike, but the ZoomX gives you a little forgiveness so your legs are not shredded over a longer effort. At 145g it is genuinely light, and the 0mm drop with a low 19mm stack keeps you right down on the track for a fast, connected feel. This is a race-day tool, not a training shoe. If your event is 1500m and longer and you want a distance spike that lets you hold pace when it hurts, the Dragonfly 2 is one of the most trusted options out there. Sprinters and 800m specialists will want Nike's more aggressive Air Zoom Victory 2 instead.