February 27, 2023
Nike changed the footwear world when it released the first production shoes with “strobel-less” construction—so why did they change it for the new Zoom X Invincible 3?
The Zoom X Invincible created a massive buzz when it launched in 2021. The thick Peba/Pebax sole provided the bounce of a marathon super shoe without the stiffness of a carbon plate. And it quickly made an impression on the testers at Heeluxe. Compared to all of the shoes tested in 2021, it performed in the top 10% of all running shoes for key perception metrics (fig 1). It also has the some of the best cushioning and energy return we’ve ever tested (fig 2).
The Zoom X Invincible 1 and 2 are hits with customers who give it high marks for cushioning and comfort despite the 2 having fit issues with Flyknit (fig 3).
Heeluxe’s teardown of the shoe uncovered a key to the Zoom X Invincible comfort: the insole came into direct contact with the midsole. This process is called a “strobel-less” construction or “tear away” strobel. This is one of the main reasons that the Zoom X Invincible has such great cushioning performance. Closer inspection of Nike products shows that Nike used this in earlier shoes, such as the React Infinity (fig 4).
Quick review: the Strobel is the bottom portion of the upper that is attached to the midsole during construction. The strobel is typically hard from absorbing the adhesives used in this process, which reduces cushioning performance of the midsole and insole.
Strobel-less construction began trending amongst Heeluxe’s customers. Brands from running, casual, work boots, hiking, and even dress/fashion categories were asking about the benefits of this construction and how to test their new strobel-less prototypes. You’ll see many new examples of strobel-less shoes entering the market in 2023 and beyond.
After the success of Zoom X Invincible 1 and 2, the Heeluxe researchers were excited to start testing the Zoom X Invincible 3, launched in Jan 2023 with a major midsole redesign. A trip to our local specialty running store, Santa Barbara Running, to see the new version led to disappointment: runners did not like the shoe as much and the strobel-less construction was gone in favor of a standard strobel. Online reviews for Zoom X Invincible 3 are much worse than the earlier versions (fig 5).
Nike is a great company with a lot of smart people working on their footwear, so there has to be a good reason why they stopped making the strobel-less construction, right?
For every other footwear brand out there, please continue to work towards incorporating strobel-less constructions in your new footwear lines. This technique improves underfoot cushioning and comfort, making a better shoe for your customer. If you’d like to learn more about how to incorporate strobel-less constructions into your product line, emailing (email@example.com) the Heeluxe team of researchers is a great place to start.
PS: Looks like we are not alone in the critique of the new Zoom X Invincible.
“It feels to me as if the energetic ZoomX has been watered down and I wish I could cut the strobel lining out of the shoe.”