Adidas Adizero Prime X2 Strung Review: Big Stack, Wild Racers Built for Going All-Out

Stack Height, Drop, Weight and Price

The first thing to note about the Adidas Prime X2 Strung is the even bigger 50mm / 43.5 mm stack height that puts it over the World Athletics legal height for midsole stack. Thought that probably only matters if you’re an elite.

There’s half a millimetre of added LightStrike Pro foam in the heel and 2.5mm added to the forefoot. That changes the drop from 10mm in the previous generation to 6.5mm in this new shoe. It also changes the ride. But more on that later.

When it comes to weight, the second-generation Adidas Prime X2 Strung is a considerable chunk heavier than the original – and every other carbon race shoe for that matter. It tips the scales at 11.6oz / 330g in my UK 8.5 test size. For comparison the Prime X Strung weighed in at 8.9oz / 251g. It’s also heavier than the Nike Alphafly Next% 2 (8.7oz / 248g), the Nike Vaporfly Next% 3 (6.9 oz / 195g) and the Saucony Endorphin Elite (7.5oz / 211g).

The US Price stays the same. The Prime X2 Strung will cost you $300. If you’re in the UK it’s now £20 more expensive up to £250. That’s still cheaper than the Alphafly Next%2, the Saucony Endorphin Elite and the new eye-watering $500 Adidas Adizero Adios Pr Evo 1.

Design

There are some significant changes to the Adidas Prime X2 Strung. Starting with an increased three-layer stack of Adidas’ light and responsive Lightstrike Pro midsole foam. That creates an even higher platform underfoot and the geometry has changed too, with a significantly lower drop and much more bouncy foam under your forefoot. 

Inside that bigger wedge of super responsive foam, there’s also now a new double carbon plate set-up that Adidas calls its Energy Core system. That’s there to provide the stiffness, spring and control. 

The uppers use the same Strung upper technology that debuted in the original Strung. The computer generated Strung technology works by strategically placing strands to build out the shoe’s support only where it’s needed most, based on athlete data. Though the more traditional design has been replaced by a new booty-style fit. 

The heel collars remain minimal and racy. There are just a couple of small foam pads inside to provide the heel hold.

When it comes to grip and durability, that’s largely the same with a covering of Continental rubber to take care of the forefoot and a couple of strategically placed pads to reinforce the heel.

Fit

I ran in my regular running shoe size, a UK 8.5. The same size I had for the original Adizero Prime X Strung. The fit is completely different thanks to the new booty-style design. I have high insteps and wide feet and I really struggle to get the Prime X2 Strung on my feet. It’s a wrestle and at times I found myself wishing I owned a shoe horn.

Once they’re on, the fit is generally ok. It’s very hugging across the top of the midfoot, as you’d expect from a race shoe. However, I didn’t find it quite as secure in the heel as the first generation. Tweaking the lacing didn’t seem to help. They’re by no means loose but there is a shade more movement than the previous shoe.

However, I’d still recommend going true to size.

Performance

I’ve run 50+ miles in the Adizero Prime X Strung 2. That includes a 1.5 hour mixed-paced run with 10km, half and marathon pace intervals, an all-out mile test and a few slower efforts to see how they cope when you’re tired. I ran mostly on road with the odd park or river path section to really test the stability.

Straight out of the box you know these are going to be lively, punchy and energetic but not great on stability. Comfort once they’re on the foot is solid. They hug the foot in a race-shoe way but there’s still a bit of flex in the toe box that makes them marathon-distance friendly. 

The ride is bold, bouncy and a bit wild and it’s got every bit of the energy sparing that you found in the original Strung. For my all-out mile test I ran one of my fastest ever miles (a 5:30) on tired legs. When you’re moving with serious intent, good form and focus, you feel the shoe giving you a helping hand.

The higher stack, lower drop and tweak geometry has changed the ride here though. The Strung X wasn’t a stable shoe by any means but this update is even less so. It’s now wobblier and harder to control around tight corners. I could feel my foot sliding off the big Lightstrike Pro bed at times. This shoe demands that you focus on landing with precision. I’ve tested hundreds of running shoes and I don’t often roll my ankles but I nearly went over twice in testing.

However, when you move with precision and intent, these are right up there with the most energetic carbon running shoes I’ve tested. They’re not only fast but they’re fun and for a straight line city marathon on a reliable road surface, they’ve definitely got PB potential.

While you can’t rely on the stability when your form gets ragged, that added midsole foam does deliver more impact protection should the wheels come off deep into longer races and you’re landing a little heavier. It does a better job of fending off the foot fatigue than some more direct super shoes like the HOKA Rocket X2 or the Saucony Endorphin Elite, for example.

My Verdict

What you get from the Adidas Prime X2 Strung is a lively, snappy, bouncy, leg-sparing ride that delivers high energy in every step. Yes, they’re heavier than the first gen (and every other carbon racer) and that probably makes them less equipped for shorter distance racing but for straight-line urban marathons, these are up there with the best race shoe options.

However, if you struggle with the booty fit, or want more stability and better cornering, and you can find the first generation Strung for its original price or cheaper, I’d probably still go for those. I think they’re easily a match – if not better – than this second generation Adizero Prime X2 Strung on many fronts. So worth looking out for.