Adizero Prime X 2 vs Vaporfly 3

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 Vaporfly 3 is Nike's carbon racing shoe for runners who want to go fast without the towering stack of an Alphafly. It is a pure road racer, built for 5k up to the marathon, and it does that one job very well. At 194g it is light, the 8mm drop keeps you rolling forward, and the carbon plate gives you real pop when you commit to race pace. This is not a shoe for plodding. It rewards a quick, efficient stride and comes alive the harder you push. If you have run in earlier Vaporflys you will know the feeling: fast, slightly twitchy, and unmistakably a tool for race day. The newer Vaporfly 4 refines the formula, but the 3 remains a serious marathon shoe, and when it drops below RRP it is one of the better-value carbon racers you can buy. We rate it for runners who already have a daily trainer and want a dedicated PB weapon.