The Nike Flex Run 2021 Review & Lab Test of 2026

The Nike Flex Run 2021, a sustainable running shoe, prioritizes comfort and usability based on both lab tests and wear evaluations. This shoe is ideal for runners seeking a lightweight option that minimizes impact during activity. With its focus on eco-friendliness, the Nike Flex Run 2021 balances performance and environmental responsibility.

Pros

  • Fits true to size
  • Good ground feel
  • No break-in period
  • Extremely lightweight
  • Flexible
  • Look great
  • Made with sustainability in mind
  • Low price point
  • Toes can wiggle

Cons

  • Durability issues
  • Grips dry tarmac only
  • Short runs only

Key Features

  • Rubber sole for enhanced traction and durability
  • Textile outer material for breathability and flexibility
  • Foam inner material that provides cushioning for comfort
  • Lace-up closure type for a customizable fit

Specifications

  • Sole material: Rubber
  • Outer material: Textile
  • Inner material: Foam
  • Closure type: Lace-Up

Nike Flex Run 2021 Review & Lab Test – Price, Ratings, Reviews & Sales Insights

Nike Flex Run 2021 Nike Free RN NN Nike Flex Experience Run 12 New Balance Fresh Foam Roav V2
Price $80 $100 $75 $85
Pace Daily running Daily running Daily running Daily running
Arch support Neutral Neutral Neutral Neutral
Weight lab Weight brand 7.9 oz / 223g 6.9 oz / 197g 8.5 oz / 241g 8.4 oz / 238g
Lightweight
Drop lab Drop brand 7.2 mm 6.9 mm 6.0 mm 7.2 mm
Strike pattern Mid/forefoot Mid/forefoot Mid/forefoot Mid/forefoot
Size True to size True to size True to size Slightly small
Midsole softness - Balanced Firm Balanced
Difference in midsole softness in cold - Small Small Small
Toebox durability - Good Decent -
Heel padding durability - Good Good -
Outsole durability - Good Bad -
Breathability - Warm Moderate Warm
Width / fit Medium Wide Medium Narrow
Toebox width - Wide Medium -
Stiffness Flexible Flexible Flexible Moderate
Torsional rigidity - Flexible Flexible Flexible
Heel counter stiffness - Flexible Flexible Flexible
Heel lab Heel brand 32.3 mm 25.6 mm 25.9 mm 32.2 mm
Forefoot lab Forefoot brand 25.1 mm 18.7 mm 19.9 mm 25.0 mm
Widths available Normal Normal Normal Normal
Orthotic friendly
Season - All seasons All seasons Winter
Removable insole
Ranking Bottom 24% Bottom 3% Bottom 5% Bottom 13%
Popularity Bottom 8% Bottom 24% Top 17% Top 32%