I ran over 30 miles in the Brooks Glycerin 21 shoes — and they’re amazingly comfortable

Brooks' cushioned shoe gets a comfort boost

Brooks Glycerin 21 on a path
(Image: © Michael Sawh)

Tom's Guide Verdict

The Brooks Glycerin 21 is a solid shoe if you’re looking for something to cover your slow, easy-paced runs, offering an accommodating fit and a softer level of cushioning to keep things comfortable even over longer distances.

Pros

  • +

    Very accommodating fit

  • +

    Plush and smooth feeling underfoot

  • +

    The outsole feels built to last

Cons

  • -

    Not ideal for high-intensity runs

  • -

    Lighter alternatives available

  • -

    Price has increased slightly compared to previous edition

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Brooks' most popular running shoe is the Ghost, but the Brooks Glycerin 21 is a great alternative. It’s designed for similar types of runs as the Ghost but also aims for a luxurious feel when you need to eat up that running mileage regularly.

The Glycerin 21 focuses on retaining that feel of the Glycerin 20 to make it a great option and has now added more cushioning while dropping the overall weight of the shoe. It’s also reworked the upper and outsole to make it a more comfortable and durable installment of the Glycerin.

I’ve run plenty in the Glycerin 20 — they're some of my best running shoes and definitely my favorite Brooks shoe to run in. So I was intrigued to see if the updates Brooks has made here make the 21 an even better version of the Glycerin.

Brooks Glycerin 21: price and availability

The Brooks Glycerin 21 launched on February 1st, 2024, and are available directly from Brooks and many other retailers priced at $160, which does mean there's been a price increase since the Glycerin 20, as they were $150 at launch. 

That cost puts them in line with other cushioned daily shoes, like the Asics Gel-Nimbus 25 and 26 and the New Balance Fresh Foam X 1080v13. And the Glycerin 21 are marginally more expensive than the Hoka Clifton 9 ($145) and the Brooks Ghost Max ($150). 

Brooks Glycerin 21 review: design and fit

Brooks Glycerin 21 side view

(Image credit: Michael Sawh)

The Brooks Glycerin 21 are available in men's and women's versions and in medium and wide fit. And there are 9 colors, so you should be able to find a design and fit that works for your style and training. 

In general, though, I found the fit of the Glycerin 21 very accommodating. I mostly tested the medium-fit Glycerin 21, but I also spent a while in the Glycerin 21 GTS — an edition designed to add stability for overpronators. 

There's a 10mm drop and a 2mm stack height increase compared to the Glycerin 20 due to the added cushioning. Weight-wise, my medium fit, US size 9s weighed in at 280g, a 21g reduction compared to the Glycerin 20. 

I have narrow feet but found the fit great overall, and going true to your usual running shoe size should be fine. My size 9 shoes had good room for my toes and I didn't have any heel slippage or irritation either. 

Uppers

Brooks Glycerin 21 uppers

(Image credit: Michael Sawh)

The Brooks Glycerin 21 have a redesigned upper that retains the comfort of the Glycerin 20's mesh upper, but feels thicker and lacks some of the previous version's breathability. But it is more supportive. 

The padded tongue and heel collar are also slightly different with new padding, but it doesn't really feel that different from the Glycerin 20. While they're available in several colors, I didn't feel that the blue, nightlight, and black versions were as stylish as other shoes I've tested. 

Midsole

Brooks Glycerin 21 midsole

(Image credit: Michael Sawh)

These shoes come with the DNA Loft V3 midsole foam introduced on the Glycerin 20, which saw Brooks join the likes of Puma and Inov-8 in adopting this new cushioning technology. 

The third iteration of DNA Loft is noticeably bouncier than the equivalent foam in the Brooks Ghost range, and it means that you get more protection, especially along longer or routine runs. 

Outsole

Brooks Glycerin 21 outsole

(Image credit: Michael Sawh)

The Brooks Glycerin 21's RoadTrack outsole is made from a mix of rubber and recycled silica and has unique patterns for different sections of your foot. I used the shoes mainly on roads and sidewalks, but also on a few trail runs. 

Despite throwing the shoes at a variety of surfaces, the RoadTrack outsole handled them all pretty well. But if you want to spend more time off-road, a pair of dedicated trail running shoes would be best. 

Brooks Glycerin 21 review: performance

Brooks Glycerin 21 side view on a path

(Image credit: Michael Sawh)

I varied my training in these shoes, but generally focused on the comfortable, easy-paced runs they're designed for, with a few uptempo sessions occasionally thrown into the mix. 

The cushioning can feel quite intense, which is great for protecting your legs and making long runs enjoyable, but I did find that, even with the weight loss compared to the 20, they're still not an especially light shoe. 

The ride doesn’t scream speed, as there’s no rocker here to quickly get you from your heel to your toe and keep you moving forward swiftly. Instead, the shoe is smooth and pleasant, with decent bounce. 

It may not be that exciting, but the comfortable ride means that my first 5km run in them was pleasant, especially at slower speeds. And they were a good companion for longer sessions on tired legs. 

The outsole felt durable too, so the shoes should clock up a lot of miles. The rubber helps temper any wildness in that bouncy ride while also giving you plenty of grip, which had no problems handling some rainier running conditions.

Should you buy the Brooks Glycerin 21?

The Brooks Glycerin 21 are a solid update to the previous edition, so they're still one of my favorite cushioned running shoes for short and long distances, especially if you're training for a race — or even on race day. 

If you like the idea of the Brooks Ghost with a bouncier and less firm feel, then the Glycerin 21 will appeal. If you prefer a plusher cushioned shoe, go for something like the Asics Gel-Nimbus 25 or the New Balance Fresh Foam X 1080v13.

Michael Sawh

Michael is a freelance journalist who has covered consumer technology for over a decade and specializes in wearable and fitness tech. Previously editor of Wareable, he also co-ran the features and reviews sections of T3, and has a long list of bylines in the world of consumer tech sites.


With a focus on fitness trackers, headphones, running wearables, phones, and tablet, he has written for numerous publications including Wired UK, GQ, Men's Fitness, BBC Science Focus, Metro and Stuff, and has appeared on the BBC Travel Show. Michael is a keen swimmer, a runner with a number of marathons under his belt, and is also the co-founder of YouTube channel The Run Testers.