Glycerin 20 vs Glycerin 21: The next step in cushioned running shoes
18th January, 2024|By Brooks Staff
The nitrogen-infused Glycerin 21 offers weightless softness, but how does it compare with its predecessor?
If you want comfort on the run, Glycerin is for you. In fact, these are the most cushioned shoes in the Brooks collection, offering supremely soft underfoot technology and silky smooth transitions. The latest iterations, Glycerin 20 and Glycerin 21, are each designed to let you focus less on your feet and more on your run, but they do so in slightly different ways. Let’s see how they stack up.
The Glycerin story: More cushion. More softness. Less gravity.
As one of our most popular cushioned running shoes, Glycerin has always prioritised comfort, protection and support—and sometimes broken new ground on the way. Back in 2018, for example, Glycerin 16 became the first shoe to feature our exclusive DNA LOFT technology for a lightweight-yet-luxurious ride.
Having been regarded by some as a recovery trainer in the early days, Glycerin is now firmly established as a high-performing daily running shoe for both long runs and speedwork. Each Glycerin launch carries that legacy forward while offering new innovations, thoughtful touches, and an even more refined balance of speed and comfort. But which Glycerin will fit your run best?
Glycerin 20 vs Glycerin 21: A side-by-side comparison
Glycerin 20 and Glycerin 21 have a shared heritage, but there are some subtle points of differentiation between the two. Here’s how they compare in five key areas:
Plush cushioning: Although both shoes feature our latest nitrogen-infused DNA LOFT v3 cushioning, Glycerin 21 has an additional 2 mm of it underfoot. That makes it our most cushioned running shoe yet.
Improved upper: Glycerin 20’s breathable air-mesh upper offers a secure and comfortable fit. Glycerin 21’s new engineered warp knit upper is also breathable but provides structure in crucial locations across the foot.
Custom fit: Both the Glycerin 20 and Glycerin 21 offer a choice of classic fit or StealthFit, which moulds closely to your foot. Both shoes are also available with go-to-support (GTS) via our GuideRails® technology.
Sole technology: Glycerin 21 is the first shoe in the Glycerin series with our new RoadTack rubber, a resilient, lightweight compound made using a mix of rubber and recycled silica.
Smooth transitions: Glycerin 20 and Glycerin 21 feature a redesigned midsole and outsole, creating a widened platform for greater stability and smoother heel-to-toe transitions.
Glycerin 20: Supremely soft yet speedy
Although it’s designed mainly for luxurious comfort, Glycerin 20 doesn’t rest on its laurels. This cushioned running shoe is packed with comfort-first innovations like a widened platform and an all-new engineered mesh upper, allowing runners to forget their feet and let their minds run free.
Featuring more of our DNA LOFT v3 foam than any other running shoe, Glycerin 21 keeps your feet feeling firmly off the ground. What’s even better is that all that comfort doesn’t come at the cost of performance - this is a balanced, lightweight blend of responsiveness and support for mile after mile of distraction-free running.
Glycerin 21 is also available in custom configurations for the right fit. Glycerin GTS 21 uses GuideRails® support to keep you moving comfortably while supporting the most injury-prone part of a runner’s body: the knees. Both the Glycerin 21 and Glycerin GTS 21 are available in StealthFit, now featuring an updated FitKnit upper that moulds to your foot for a blend of stretch and compression. This new configuration is designed to move with you, while the new materials feel super soft against your foot.
Hello Glycerin, goodbye gravity
There’s no question that Glycerin 20 and Glycerin 21 each set new standards in plush comfort. With its ground-breaking use of our nitro-infused midsole technology, Glycerin 20 remains an excellent choice for runners who want supremely soft cushioning that lets them free their minds and get lost in the run.
In subtle contrast, its successor offers additional DNA LOFT v3 foam, resilient RoadTack rubber, and a snug redesigned upper. That makes Glycerin 21 the ideal choice for runners who enjoy distraction free movement and super soft cushioning underfoot, especially over longer distances.
Ultimately, it all comes down to your running habits and personal preferences. If you still can’t decide, remember that our Run Happy Promise means you can put your new shoes to the test for 90 days. If you don’t love them, return them for free.
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Disclaimer: Our writer's advice is intended for informational or general educational purposes only. We always encourage you to speak to your doctor or healthcare provider before making any adjustments to your running, nutrition or fitness routines.