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Nike

Air Zoom Structure 21

Air Zoom Structure 21
Daily trainer · Stability · Road
Below average (54/100)

Shoe details

Weight
10.4 oz
Release
2017 Q3
MSRP
$120
Drop Height
10mm

Ratings & Reviews

Below average (54/100)

Better than about 3% of shoes

Based on product-line history, external ratings, and runner reviews.
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This score rates worse than 97% of shoes.

Our ratings use detailed reviews from knowledgeable runners, ratings for shoes in the same product line, and reliable product information from trusted retailers.

Rating breakdown

Better Shoes score out of 100. Shading shows the expected rating range.
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Rankings combine runner ratings, whether reviewers say they'd buy a shoe again, direct comparisons to other shoes, related product-line performance, and trusted external ratings.

The darker band shows the central score range. The lighter band shows a wider range of reasonable outcomes. More reviews for this shoe usually narrow both bands.

Overall

Below average (54/100)

Overall ranking

We estimate how this shoe ranks by combining runner ratings, whether reviewers say they'd buy a shoe again, and direct comparisons to other shoes they've run in. We also consider related product-line performance and trusted external ratings. More review data helps narrow the likely rating range.

Estimate

Below average (54/100)

Rank

Ranks above 3% of shoes

Compared with all shoes

The shaded band shows the score range we think is most likely.

Appearance

Above average (85/100)

Appearance ranking

We estimate how this shoe ranks by combining runner ratings, whether reviewers say they'd buy a shoe again, and direct comparisons to other shoes they've run in. We also consider related product-line performance and trusted external ratings. More review data helps narrow the likely rating range.

Estimate

Above average (85/100)

Rank

Ranks above 73% of shoes

Compared with all shoes

The shaded band shows the score range we think is most likely.

Durability

Above average (83/100)

Durability ranking

We estimate how this shoe ranks by combining runner ratings, whether reviewers say they'd buy a shoe again, and direct comparisons to other shoes they've run in. We also consider related product-line performance and trusted external ratings. More review data helps narrow the likely rating range.

Estimate

Above average (83/100)

Rank

Ranks above 72% of shoes

Compared with all shoes

The shaded band shows the score range we think is most likely.

Cushioning

Good (72/100)

Cushioning ranking

We estimate how this shoe ranks by combining runner ratings, whether reviewers say they'd buy a shoe again, and direct comparisons to other shoes they've run in. We also consider related product-line performance and trusted external ratings. More review data helps narrow the likely rating range.

Estimate

Good (72/100)

Rank

Ranks above 43% of shoes

Compared with all shoes

The shaded band shows the score range we think is most likely.

Value

Below average (65/100)

Value ranking

We estimate how this shoe ranks by combining runner ratings, whether reviewers say they'd buy a shoe again, and direct comparisons to other shoes they've run in. We also consider related product-line performance and trusted external ratings. More review data helps narrow the likely rating range.

Estimate

Below average (65/100)

Rank

Ranks above 20% of shoes

Compared with all shoes

The shaded band shows the score range we think is most likely.

Comfort

Below average (54/100)

Comfort ranking

We estimate how this shoe ranks by combining runner ratings, whether reviewers say they'd buy a shoe again, and direct comparisons to other shoes they've run in. We also consider related product-line performance and trusted external ratings. More review data helps narrow the likely rating range.

Estimate

Below average (54/100)

Rank

Ranks above 3% of shoes

Compared with all shoes

The shaded band shows the score range we think is most likely.

41%

7/17

Prefer this shoe over another.

Reviewers said this shoe was better than another shoe they ran in.

All Running Shoes

Worse than 97% of 2,541 running shoes ranked.

Below average (54/100)

Daily Trainers

Worse than 97% of 1,841 daily trainers ranked.

3%

Nike

Worse than 93% of 420 Nike shoes ranked.

7%

Pros & Cons

Pros

  • Popular shoe among LetsRun.com readers.
  • Rated above average on cushioning.
  • Rated among the top 25% of shoes on durability.

Cons

  • Rated below average overall.
  • Rated among the bottom 10% of shoes on comfort.

Compared to other shoes

See how this shoe compares to others like it.

Nike Air Zoom Structure 21
Nike Air Zoom Structure 23
ASICS SUPERBLAST 2
Air Zoom Structure 21
Air Zoom Structure 23
SUPERBLAST 2
Current shoe
Reference shoe
Newest / Best overall / Best comfort
Shoe properties
Type
Daily trainer
Daily trainer
Daily trainer
Pronation
Stability (Moderate)
Stability
Neutral
Weight
10.4 oz M
—
—
Stack
—
—
—
Drop
1mm
—
7mm
Release
2017 Q3
2023 Q4
2024 Q2 Newest
MSRP
$120 Lower MSRP
—
$200
Best price
—
—
$149.99
Ratings
Overall
Bottom tier (3%)
Bottom tier (5%)
Exceptional (>99%) Best overall
Comfort
Bottom tier (3%)
Bottom tier (5%)
Exceptional (99%) Best comfort
Cushioning
Average (43%)
Bottom tier (16%)
Exceptional (99%) Best cushioning
Durability
Good (72%)
Average (53%)
Exceptional (99%) Best durability
Appearance
Good (73%)
Above average (66%)
Excellent (96%) Best appearance
Value
Bottom tier (20%)
Average (42%)
Very good (85%) Best value
Specific shoe

Search for the exact model to add to this comparison.

Where to buy

No offers available

Better alternatives

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70th percentile

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68th percentile

+65 percentile points vs this shoe
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64th percentile

+61 percentile points vs this shoe

More from Nike

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21st percentile

+18 percentile points vs this shoe
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98th percentile

+95 percentile points vs this shoe

Reader Ratings

14 reader ratings

Review a shoe

Showing 1–5 of 14 written reviews

Structure 21 Experience

Anonymous runner · Nov 21, 2018

4/5

Overall

This is my most commonly purchased shoe, it tends to fit my foot very well. There is just enough cushioning, although not an overwhelming amount. I felt as if there is more cushioning in the forefoot than the Structure 20. It is not very flexible, due to the dynamic stability feature in the midsole, but for those that wear support shoes, this is no surprise. They did a great job with the design of this shoe, with the color fade on the lateral side of the midsole, in my opinion. Overall, I am very happy with this iteration, Nike continues to make a great support shoe.
Comfort
4/5
Cushioning
4/5
Durability
4/5
Appearance
5/5
Value
4/5

Needs a break in period

RoseCityTC · Oct 16, 2018

4/5

Overall

I found that after 50-100 miles these shoes really become comfortable and my go to trainer for easy runs.
Comfort
4/5
Cushioning
4/5
Durability
5/5
Appearance
4/5
Value
5/5

Great shoe, but I'd never pay full price for it

Ball Zach · Oct 3, 2018

4/5

Overall

This shoe was my first foray into serious training in Nikes. Previous shoes were mostly Brooks Ravennas and Saucony Guides. I'm a bigger guy (6'3" 180 lbs) but still train pretty seriously (low 15's 5k, mid 25's 8k, 70ish half). What I find with being bigger is that I blow out the cushioning before the tread really begins to wear down. This can happen within 6-8 weeks, so I go through shoes pretty quick. The Structures have lasted beyond that average, but with how ridiculous shoe prices have gotten (around $120 for a standard shoe) I would never pay full price for them. It's just too much money to throw away. All in all, the Structures are a great shoe, but they're not $120 great.
Comfort
4/5
Cushioning
4/5
Durability
4/5
Appearance
5/5
Value
3/5

Good stability shoe

jandre78 · Oct 3, 2018

3/5

Overall

Nice soft ride and good support. I had to swap the inner soles as the originals caused blisters on longer runs
Comfort
3/5
Cushioning
3/5
Durability
3/5
Appearance
3/5
Value
3/5

Solid trainer

Anonymous runner · Oct 3, 2018

5/5

Overall

I've enjoyed returning to Nike's. The shoe has been responsive, light, and pretty durable. I just hate the price tag. Then again, I think all shoes are overpriced now as I used to be able to buy a nice pair of trainers for $70-80 10 years ago.
Comfort
5/5
Cushioning
5/5
Durability
4/5
Appearance
5/5
Value
4/5