Adizero Prime X 2 vs SC Elite 4

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 New Balance SC Elite 4 is a full-fat carbon marathon racer, and it wears that brief proudly. This is a tall, soft, aggressively cushioned racing shoe built to keep your legs alive deep into the back half of a marathon rather than to feel featherlight off the line. At 237g it is on the heavier side for a carbon racing shoe, so it does not have the darty, snappy feel of a lighter racer like the Nike Vaporfly 4. What you get instead is a big, forgiving platform and a rolling, momentum-holding ride once you are up to pace. With a 4mm drop and a full carbon plate it sits firmly in the marathon-and-half super-shoe class. At £280 RRP it is a premium buy, but for a runner who wants cushioning and protection over knife-edge sharpness, it is one of the more comfortable ways to race a long road event.