Brooks Glycerin 21 Review (2024): Ultimate Confort?

Charlène Bertein

Published on 04/24/2024

The Glycerin is one of Brooks’ most classic shoes. Renowned for its comfort and cushioning, it’s ideal for jogging and long runs.

In this detailed review of the latest version, the Brooks Glycerin 21, I reveal everything you need to know before buying these shoes. My assessment is based on my field tests and a literature review from other runners with different backgrounds to make sure my recommendations are relevant to as many people as possible.

Our Verdict

Cushioning

Until the arrival of the Brooks Ghost Max, the Glycerin 21 was Brooks’ most cushioned shoe. DNA LOFT v3 technology, a nitrogen-infused foam, absorbs shock to provide soft, slightly firm cushioning.

This new version features 2 mm more foam than its predecessor. This gives a stack height of 38 mm at the heel and 28 mm at the front.

The 10-mm drop is standard, if not a little high these days.

This model is very comfortable and can accompany you on long runs. Distances such as the half-marathon or marathon are also possible if you’re not looking for high-performance shoes to chase a new Personal Best in your race.

Energy return

The Brooks Glycerin 21 is not a responsive shoe: its bounce is very gentle but doesn’t propel much forward. However, despite the lack of rocker and carbon plate, transitions from heel to toe are smooth and pleasant. Nothing is holding you back to pick up the pace, but the shoe’s design doesn’t encourage it either.

With 249 g/8.8 oz for the women’s model and 276 g/9.7 oz for the men’s, they are not lightweight shoes, even though there’s been a clear improvement over the years. Nowadays, this is quite standard and in line with the level of comfort, protection, and durability the shoes offer.

What’s more, I didn’t notice the weight when I was running–instead, I experienced a sensation of lightness.

Support and stability

The Glycerin 21 shoes are stable and suitable for most runners.

If you’re an overpronator who needs supportive features to help guide your stride, you should take a look at the GTS (Go-To-Support) version, which has GuideRails technology for more excellent stability.

Foot Lockdown

The new engineered knit is softer than the previous version and very pleasant to wear. You feel very comfortable when you put on the shoes for the first time.

On the other hand, the stitches are tighter, and the material is a little thicker than before, which decreases breathability compared to the Glycerin 20. I tested these shoes in winter, so this didn’t bother me, and I enjoyed the protection from the cold. However, I can imagine it could be a different story in the summer.

The Glycerin 21 runs true to size, and the toe box is slightly wider. Also, there’s a wide version for runners with wide feet who need a little extra space to be comfortable (same price).

The upper perfectly wraps around the foot for a very good lockdown. The padded tongue is not gusseted, but I didn’t notice any excessive slippage. The heel counter is also effective in locking the foot and preventing slippage.

However, some runners miss the flat laces of the previous version, which allowed a more precise foot lock and fit than with the new ones. I agree: the new oval-shaped laces are thinner and seem to fray more quickly.

Traction

The outsole is quite different from last year’s. Segmented RoadTack rubber in the forefoot gives the shoe more flexibility while still being very durable.

I found the Brooks Glycerin 21 to grip very well on wet surfaces. You can also use them on easy trails, such as gravel or dirt paths, as I did (I live in the beautiful mountains surrounding Grenoble in France).

Use

This pair of shoes is ideal for low-pace runs, recovery jogging and long runs. Although they are not very responsive, they can be used occasionally for more intense tempo sessions.

If you’re looking for performance in your races, this model is certainly not for you! In that case, opt for more responsive shoes, with or without a carbon plate, to reach your goal.

Quality and Durability

From my experience and other testers, the sole of the Glycerin 21 is durable and shows no signs of early wear. The mesh is also very sturdy, with its tightly knitted construction.

Based on these elements, we estimate a potential lifespan of 800-1,000 km/500-650 miles, depending on your weight and gait. This is quite above average. Only the laces are likely to snap earlier, but this is an easy and inexpensive component to replace.

The price is standard for its category, making the Glycerin 21 great value!

For many years, Brooks has been committed to taking a long-term approach to offering sustainable products. While not carbon neutral like the Brooks Ghost 15, the Glycerin 21’s upper is made from 60% recycled materials, the equivalent of 4 plastic bottles.

These shoes are entirely vegan.

Alternatives

Brooks Glycerin 20

The Brooks Glycerin 20 and 21 have many features in common, but there are some notable changes between the two versions.

Although the cushioning used is similar (DNA LOFT v3 with nitro-injection), the Glycerin 21 offers 2 mm more, making the shoe softer.

As for the upper, version 21 is made of technical knit, which was not the case with its predecessor. Breathability is not as good as before, but the new mesh provides more structure in certain areas of the foot.

Finally, the RoadTack rubber is a new feature, offering excellent traction on wet and dry roads.

If you liked the Glycerin 20, the new version should suit you, too, with even greater comfort. However, it may be worth opting for the previous model if you can find it during promotion periods.

Other options

• Brooks Ghost 15: The Ghost is the American brand’s most popular model. It is narrower and less responsive, but it is more resistant, as it has more rubber on the outsole (read the detailed comparison).
• Brooks Adrenaline 23 GTS: GTS technology guides the foot to avoid overpronation. There used to be a non-GTS version of the Adrenaline, but this no longer seems to be the case (keep an eye on it). Clearly, the comparison is more apt with the Glycerin GTS, which we haven’t tested. However, on paper, the Glycerin is more responsive with its newer foam. It’s also lighter and more cushioned – so the choice seems obvious (see our Brooks Adrenaline vs. Glycerin article).

Conclusion

The Brooks Glycerin 21 are comfortable shoes with good cushioning, perfect for jogging and long runs. With their excellent grip, you can use them on wet roads and easy trails. They suit beginners and experienced runners, provided you’re not looking for performance. Also, their high-quality means you can enjoy their superior comfort for several hundred miles.

Facts

Technical Specs

Cushioning

Technologies

Use