Brooks Glycerin 21 Designed for Slow Leisurely Runs

Last updated on February 16th, 2024

Glycerin 21 toebox

The Brooks Glycerin 21 is a solid choice for a highly cushioned running shoe that provides ample support. Designed for slower runs, it offers a decadently comfortable experience with its plush landings. Although it may not have the most energetic ride, it exudes a sense of luxury. The updated Glycerin 21 boasts a knitted upper that is not only more comfortable but also provides a wider toe box. Additionally, with an extra 2 mm of stack height, this version delivers an even softer and more cushioned ride compared to its predecessor.

If you weigh more than 90 kilograms and enjoy running, or if you prefer your highly cushioned running shoes to have stability rather than excessive softness, then the Glycerin 21 is an excellent choice.

If you are seeking a shoe that delivers a heavenly ride akin to the Nimbus and Invincible Run, the Glycerin 21 may not be the ideal choice for you.

The Glycerin 21, as described on the official Brooks website, offers exceptionally comfortable cushioning that is incredibly soft.

Glycerin 21 heel/sole

The Glycerin 16 was my initial experience with this shoe, quite a while in the past. It didn't possess the same level of softness it does now, and even after five more versions, like the Glycerin 21, it still maintains a similar level of firmness. However, I do concur with Brooks that it remains incredibly comfortable. In fact, the Glycerin series has consistently been some of the most comfortable trainers I have ever had the pleasure of wearing.

Brooks' Glycerin is a highly cushioned trainer that stands out for its softness. However, when compared to other brands' max-cushioned trainers such as the Invincible Run, the More, and the Nimbus, the Glycerin offers a noticeably firmer ride. As a result, it becomes an ideal choice for heavier runners who seek stability and durability.

The Glycerin 20 from last year was a significant upgrade for the Glycerin line. It made a noteworthy change by replacing the traditional EVA midsole with a cutting-edge, Nitrogen-infused midsole. This alteration resulted in a more comfortable experience while walking and a more stable one while running. The advanced foam used in this update allowed for quicker decompression after each step.

The latest edition of this year keeps the same DNA Loft v3 midsole, but its shape has been altered. Additionally, it features a fresh upper and outsole.

Glycerin 21 quarter

Weighing in at 278 g (9.8 oz), the Glycerin 21 is a remarkable 8 g (0.3 oz) lighter than its predecessor, the Glycerin 20. This is quite impressive, especially when you consider that the 21 has an additional 2 mm of stack height in both the heel and forefoot. It maintains a 10 mm drop and is priced at $160.

For my second run of the day, I decided to take it easy and go for a slow 8 km recovery jog. My legs were tired, so I didn't want to push myself too hard. As I started running, I immediately noticed the raised edges in the front and middle parts of my foot, and it was quite bothersome.

It was unexpected, considering that this is the standard Glycerin and not the GTS edition. Fortunately, this feeling vanished after covering the initial 3 kilometers.

During the run, the shoe offered ample protection, leaving my legs feeling content. The cushioning wasn't extremely plush, but it struck a good balance, resembling a daily trainer rather than a highly cushioned one. The upper fit snugly and provided exceptional comfort and flexibility.

The Glycerin 21 didn't quite give me the same impression as the Aurora-BL, another shoe from Brooks. It lacked the same level of softness, energy, and distinctiveness. The Aurora was the trailblazer in incorporating DNA Loft v3 technology.

Glycerin 21 upper

The Glycerin 21 boasts an opulent upper that is generously cushioned and lined with a silky smooth material. I have encountered no problems with discomfort or the shoe slipping off my heel, but I do find it to be exceptionally warm.

The Glycerin 20 now features a fresh, knitted upper that offers a gentle and smooth feel. However, this new material sacrifices some of its breathability compared to the previous mesh upper. On the plus side, the knitted upper is more flexible and molds snugly to the shape of your feet. Additionally, it is visibly thicker than its predecessor.

The tongue of the shoe is not gusseted, but it does not slide excessively because it has a loop for the laces to pass through. The laces have been replaced with soft, thin oval laces that tend to unravel easily. Personally, I prefer the flat laces found on the previous version as they give a more high-quality sensation.

The Glycerin 21 comes in both narrow and wide sizes, providing options for different foot shapes. In terms of length, it is slightly shorter than your typical running shoe, although it still maintains a true-to-size fit. Additionally, compared to its predecessor, the Glycerin 20, it boasts a wider toe box for added comfort.

Glycerin 21 sole units

The primary and most remarkable enhancement to the sole component is the inclusion of side rails on the outer edge of the front and middle sections in the Glycerin 21. These rails serve to align your feet and provide a sense of stability, much like the Glycerin GTS edition. However, I personally did not observe a significant change.

As a person who lands on my heel when running, I believe this shoe may be more suitable for those who strike with the front or middle part of their foot. In my opinion, the Glycerin 21 doesn't require the addition of side rails. The GTS version already includes these for individuals who require additional stability, and the regular version of the shoe is already quite stable for neutral runners even without them.

The Glycerin and the Hoka Bondi are both trainers with maximum cushioning. They provide a solid yet comfortable running experience, perfect for those seeking stability without excessive softness.

The Glycerin 21 proves to be an exceptional choice for extended running sessions, as it boasts impressive cushioning while providing adequate ankle support through its moderately firm midsole. During my recent 35-kilometer leisurely run, I relished in the remarkable comfort and durability it offered. Notably, the 21st iteration features a slightly wider design compared to its predecessor, version 20, to accommodate the heightened stack height, resulting in enhanced stability.

Despite the presence of numerous minuscule nitrogen bubbles in its DNA Loft v3 midsole, which give it a highly advanced quality, the Glycerin 21 does not possess the anticipated level of responsiveness. It provides ample cushioning and effectively absorbs shock, but it lacks the ability to inspire fast-paced running. The Glycerin 21 is best suited for leisurely, unhurried runs. I reserve it specifically for my relaxed runs and recovery sessions.

The Glycerin 21 lacks a noticeable curve in the front part of the shoe, resulting in a flat sensation when compared to the innovative Brooks Ghost Max. The Ghost Max offers quicker shifts and a firmer front section. Additionally, the Glycerin 21 is more pliable than its predecessor, version 20, resulting in a less responsive feel.

The Glycerin 21 features a distinct outsole design that sets it apart from its previous model. It has a reduced amount of rubber on the midfoot, resulting in a lighter weight. Additionally, the forefoot of the 21 outsole is divided into smaller segments, enhancing its flexibility. The rubber lugs on this model are thick and long-lasting, ensuring that durability is not a concern.

Glycerin 21 mudguard

The midsole foam that is visible is also incredibly durable and will not display many marks or damage. Even after covering a distance of 80 kilometers in my shoes, there is hardly any visible wear on the outsole.

I've tested out the Glycerin 21 in rainy conditions multiple times, and I can confidently say that I never experienced any slipping. However, it's worth noting that the traction on wet surfaces is just average. The rubber lugs on the shoes are not particularly aggressive in providing grip.

The Glycerin 21 lacks the exceptionally plush cushioning that Brooks promotes, but that's not a deal breaker. Not everyone desires a highly cushioned trainer with a soft feel.

As a light runner weighing 60 kilograms, I find that my preference lies in lighter and more springy max-cushioned trainers. However, I don't believe I am reaping the benefits of the Glycerin's sturdy construction, resembling that of a tank.

The Glycerin 21 distinguishes itself among other heavily cushioned trainers due to its durability. With a sturdy outsole and a long-lasting midsole foam, it is designed to withstand a lot of wear and tear without losing its shape.

Version 21 surpasses version 20 by offering a smoother, more cushioned journey as a result of the heightened stack height, and it boasts a cozier upper that features a roomier toe box for enhanced comfort.

In my opinion, the Glycerin can benefit from a higher midsole and a more noticeable rocker to facilitate smoother transitions. I am hopeful that the upcoming release of the Glycerin Max will incorporate these enhancements.

  • Price: $160 (Brooks)
  • Color: Grenadine/Salsa/Black
  • Usage:
    • road running shoes
    • slow leisurely runs
    • recovery/relax runs
  • Constructions & Features:
    • wider toe box than its previous version
    • knitted upper
    • soft, thin oval laces
    • Nitrogen-infused midsole
    • DNA Loft v3 midsole
    • side rails on outer edge of the front and middle sections
    • less rubber on the midfoot for a lighter weight than its previous version
    • 59.7% recycled materials in the upper
    • heel drop: 10 mm
    • weight 9.8oz / 277.8g
    • maximum cushion / neutral support
Glycerin 21 midsole