NOT A SHOE EXPLOSION! Zion Williamson and the broken Nike PG 2.5

Very rarely do we get to see first hand the failure of an athletic shoe on national television. Last night, basketball superstar Zion Williams, the 6 ft 7 in 285 pound Duke player, was injured in a fall as his Nike PG 2.5 shoe failed. As a footwear professional, I hate the popular headline “Nike sneaker explosion injures Duke star Zion Williams.”

This shoe failure is not an “explosion.” There is nothing in a modern sports shoe that can “explode.”

What I  see from the photos is that Zion Williams applied enough pressure on the on the side wall of the Nike 2.5 to break the Strobel stitching. In photos, you can clearly see the shoe separated at the Strobel seam. The outsole rubber is also torn and the side wall of the EVA midsole has ripped.

I would not look at the EVA and rubber parts as a cause of the failure. The side wall of the midsole can provide some strength, but EVA is a cushioning material. The Nike PG 2.5 failed because of tension as Williamson’s foot pushed through the Strobel seam.

Looking at the photos of the broken Nike PG 2.5, it’s hard to tell what part of the Strobel seam failed. The Strobel seam has three parts to consider:

1. The Strobel sock or Strobel board
2. The upper material
3. The stitching thread

Broken Seams

When looking at any failed footwear seam you must consider several factors:

1. Is the shoe material subject to the “perforation effect?”
   Too many stitches and stitches too close together can weaken the material.
2. Was the seam allowance wide enough?
   Similar to the perforation effect, if the stitching is too close to the edge of the shoe the material can fail?
3. Is the thread strong enough?
4. Are there enough stitches per inch ?

I do have one final thought in this case. I would like to know if the footbed was glued in to stop it from sliding inside the shoe and also if Williamson’s socks and the top surface of the footbed have enough friction to hold his foot in place? If the shoe was poorly fit to his foot, and his foot was allowed to slide inside, this may have been a contributing factor.

As this story develops I look forward to hearing more about what happened. Of course, we all wish Zion Williamson a speedy recovery.