Adidas Prime X Strung 2 Review: A Surprisingly Stable Super Trainer

Introduction

The original Prime X was one of the most polarizing running shoes in recent memory: a 50mm heel stack that felt unstable and, frankly, terrifying to run in, yet somehow stayed fairly light and delivered remarkable bounce. The Prime X Strung 2 is a completely different shoe. Despite the name, it shares far less with its predecessor than you might expect, and that difference is mostly good news.

With about 30 miles on a test pair and a plan to take it to 100 miles, the short version is this: the Strung 2 is a surprisingly stable super trainer that handles easy runs, long runs, and marathon-effort work with far less drama than the original ever managed.

Specs at a Glance

Adidas lists the Strung 2 at 10.4 ounces for men and 9.9 ounces for women’s size 8, with a size 10 men’s pair coming in around 11.5 ounces on the scale. The stack is 50mm in the heel and 43.5mm in the forefoot for a 6.5mm drop, similar to what the Adios Pro line moved into. The stack height puts it above the legal limit for World Athletics competition, so this is not a racing option for professional athletes, though recreational runners can use it however they like, including in triathlons. The outsole setup is broadly similar to the Adios Pro 3.

Fit and Upper

This version finally fits true to size, where earlier Prime X models ran slightly long. The strung upper is more flexible than before, with an integrated tongue instead of a separate one. Getting the shoe on takes effort if you have a normal to high-volume foot, and the integrated tongue tends to flip down while putting it on, but once on, it feels like a soft sock and disappears.

One practical warning: do not wear it sockless. The strung material is scratchy, so at least thin socks are a must. There is no aggressive heel counter, which is great for sensitive heels, and the collar sits low against the foot. Some heel slippage showed up initially, but a lace lock using the extra eyelets at the top solved it completely.

Ride and Performance

The original Prime X midsole was super bouncy in an Adios Pro 2 kind of way. The Strung 2 is not as bouncy at easy paces, where it feels almost like a normal, if much taller and broader, trainer. That changes when you put real force into the ground. On a hilly threshold run at around 6:20 pace, the shoe suddenly came alive and delivered a smooth, rolling ride that felt far better than expected for an 11.5-ounce shoe.

Easy runs, up-tempo runs, and marathon-pace efforts all work well here. It is a phenomenal long run shoe, and unlike many super shoes, easy paces do not feel unnatural. Two carbon fiber rods replace the plates of the previous versions, and the forefoot feels less harshly stiff, rolling more naturally through toe-off. Riders who found the original Prime X too wobbly will notice the difference immediately: the platform is wide from midfoot through forefoot, and the ride simply does not wobble.

Stability and Biomechanics

This is where the Strung 2 gets genuinely interesting. The strongly angled lateral heel bevel almost creates a wedge effect: if you land on the lateral heel, the midsole geometry guides you toward the medial side. For runners who need a touch of medial stability, this works remarkably well, almost like a borderline stability shoe despite the towering stack. Sidewalls rise mildly from heel to midfoot, adding to the guidance, and an extra band of material on the medial side raises that edge further.

The flip side matters just as much: if you have lateral stability issues or tend to roll inward excessively toward the lateral edge, this shoe may work against you. The guidance continues into the forefoot, where the rocker seems to angle slightly laterally, offering subtle medial forefoot support during toe-off.

There is also a three-layer Light Strike Pro midsole. The top and bottom layers are fairly classic, but the middle layer is an unusually soft version of the foam, with an additional wedge of it centered in the heel. A softer central layer between firmer outer layers is good guidance in itself, since the foot sinks into the center rather than drifting side to side. How three foam densities of different stiffness interact biomechanically is still an open question, but the result on the foot feels smooth and stable.

Durability and Value

At $300, the Strung 2 is genuinely expensive. Early durability signs are good: 30 miles in, the outsole shows essentially no wear, and given how well comparable Adidas midsoles have held up in the past, there is reasonable confidence it will go a lot of miles. Some reports mention a small piece that can rip off, but nothing concerning so far. If it tracks anything like other premium trainers that have reached 200 miles without significant outsole wear, the price becomes much easier to justify. Catching it on sale would make it an easy recommendation.

Buying Advice

The Prime X Strung 2 is best understood as a versatile super trainer rather than the outlawed super racer its predecessor was. It suits runners who want a very tall, well-cushioned long run shoe that can also handle marathon-pace and threshold work, especially those who need a bit of medial stability. It is a poor fit for runners with lateral stability issues in the heel and for anyone chasing the aggressive, hyper-bouncy race feel of the original Prime X. If you loved that old feel, look for the earlier versions on sale instead.

Conclusion

Adidas took a shoe that was fascinating but frightening and rebuilt it into something far more usable. The Prime X Strung 2 trades some of the wild bounce for genuine stability, a true-to-size fit, and versatility across easy runs, long runs, and tempo work. It will polarize runners, but for those who found the original too unstable and have the budget, it is one of the most interesting tall-stack trainers available.