Adizero Prime X 2 vs Zoom Fly 6

The Adizero Prime X 2 is adidas going deliberately over the top. It is a supermaximal carbon running shoe with a stack so tall it sits above the World Athletics limit, which means it is not legal for record-eligible racing. That is the whole point. Freed from the rules, adidas piled on Lightstrike Pro foam and a set of carbon EnergyRods to build a long-run and marathon-training shoe that returns huge energy with almost no legs cost. You feel launched forward once you are up to pace. At 285g it is heavy for a carbon shoe, and the ride is more cruise missile than nimble racer. If you want a legal marathon racer, the Adios Pro 4 is the sibling to buy. If you want the most protective, most propulsive daily and long-run tool adidas makes, and you do not care about race legality, this is it.

The Nike Zoom Fly 6 is the carbon plate experience for everyone who is not racing. It sits in the super trainer slot: a plated, well cushioned road shoe built to handle tempo work, long runs and the odd race without the price or the fragility of a true marathon flat. At 265g it is no featherweight, and that is the point. Nike has traded the raw speed of its race line for durability and a more forgiving daily ride, so you get the snap of a full length carbon plate stacked on a soft, bouncy midsole that holds up over the miles. If you want the actual race rocket the Vaporfly 4 is lighter and faster, but the Zoom Fly 6 is the one you can train in week after week. We rate it as one of the best value carbon trainers around for runners who want one shoe to cover their faster days.