NIKE Men's Air Zoom Structure 21 Running Shoes

Product Information

The 21 is my first experience with the Structure line, so I asked a friend of mine who loved the 18th and 19th models what he thought of the 20.

When it comes to popularity, the Structure series comes nowhere near the likes of the Pegasus or the Infinity. I personally prefer the Structure to both the Peg and the Infinity because its upper is more padded and the cushioning feels more substantial but I think that most runners still think the Structure is an old school, traditional stability trainer. The Structure 20 simplified the design by toning down the medial post and reducing the number of foam densities to two. There are other subtle changes, all of them for the better. The upper has larger vented areas. The forefoot breathes better, and so does the rearfoot which now gets vented sections over the Flywire cords. The Structure 23 felt like a supportive neutral trainer, not a “true” stability trainer. I reviewed both the Structure 23 and 24 (the 24 was only an upper update). I found them to be the best versions of the Structure to date because they felt stable and supportive without the firm ride or poking arch sensation that you normally associate with stability trainers.Turns out I still much prefer Odyssey for fast running, and the loose fit of Structure 21’s heel was even more apparent after being reminded of the snug heel fit of Odyssey. However, the Zoom Structure 21 is significantly lighter than the 20. The heavier weight of the latter means that users are more likely to suffer from foot fatigue. The Flymesh upper of the 20th version provides structural support while promoting air circulation throughout the shoe. In contrast, the 21st iteration features a lightweight seamless wrap-knit mesh which envelops the foot and expands to mould around the shape of the foot for a second-skin fit. Alternative Nike Running Shoes

The shoe that it reminded me of most was the Infinity Run 3. Both shoes have heel clips as well as prominent arches but the Structure 25 felt firmer than the Infinity Run 3. The rearfoot rides flat because there’s nothing there except for the dual-density foam and the outsole. Though the open foam area below the heel plus the removable insole helps with the cushioning, the rearfoot is noticeably firm. When I walked around in the Structure 25 for the first time, it was noticeable how much more it felt like a stability trainer than the last 2 versions. There was a prominent arch sensation which wasn’t there since the Structure 19 but it wasn’t painful or uncomfortable. My podiatrist informed me that one’s preference in drop height of a shoe relates to one’s Achilles flexibility—but no two people are alike in terms of an exact “if this then that” diagnosis: you’ll have to try out a few different types to see what really works for you. Nike Zoom Structure 21 General Info

This workout session cemented in my mind that Structure is more suited for mid to long distance runs than speedwork and that the more loose heel really does bother me. The Structure is Nike’s support shoe with a traditional design. This means that the dual-density midsole has a very firm inner side and a slightly less firm outer side. The Structure 20 balanced the two different levels of firmness extremely well. The Structure 21 has an identical midsole, so the ride exhibits the same qualities. DESIGN AND MATERIALS My first impression of Structure 21 was that it’s a shoe with a flat insole (I like at least a little more arch) that was otherwise unremarkable (which isn’t always a bad thing). The midfoot upper really snugged up nicely, though—that surprised and impressed me. Expect 400 miles of life from the Structure 21, with the wear and tear of the midsole cushioning and outsole happening in a gradual fashion. UPPER FIT AND FEEL