Adizero Prime X 2

Expect a soft, deep ride with almost no ground feel, and a stiff forefoot that tips you forward onto your toes. Reviewers enjoyed it most between easy and marathon pace. Push harder and the weight starts to tell: testers described it as bottom-heavy, and one only really liked it running downhill. Next to a lighter racer like the Alphafly 3, you trade pop for protection.

Cushioning is the reason to buy it. The forefoot alone stands 43.5mm tall, more than the heel of most daily trainers, and reviewers found their legs still felt fresh late into long runs. Those who ran both versions mostly said the bounce is tamer than the first Prime X, which some missed and others were glad of.

It's much steadier than version 1. The base is wider, and lab testing found it surprisingly stable for its height. It is still a very tall shoe, though. One tester felt quite unstable at first and settled in over time, and another review picked up a medial bias that will suit some runners and not others. Do your first few runs on straight, even roads rather than twisty paths.

Nobody had much bad to say about the upper. It hugs the foot, breathes well and cured the heel rubbing some runners got in the original. With a thin tongue and minimal heel padding, the fit depends on getting the lacing right.