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Brooks Glycerin GTS 21 Review: Providing Stability for Runners


The Brooks Glycerin line debuted in the early 2000s as a high-cushion, neutral running shoe aimed at runners seeking a softer and smoother ride. It received the GTS label on the 19s, indicating that the GuideRails technology from this brand had been introduced to it.

The GuideRails replaced the Transcend line for the brand, offering natural support and stability for running in most conditions.

Brooks works with biomechanical experts to meet expectations while remaining innovative and passionate about what they do. From gait analysis to targeted engineering, you’re getting a supportive shoe for your training.


When reviewing the features of the 21s, here are the standout points for runners who want a structured and supportive training shoe.

  • Brooks has incorporated the GuideRails tech into the design to provide holistic support through limited excess foot movement.
  • The combination of EVA foam, rubber, and air at the midsole provides comfort while training without sacrificing the product’s durability.
  • It uses an engineered mesh that gives the shoe some flexibility while delivering enough ventilation to remove hot areas.
  • A strategic 3D-printed strategic overlay is added to the upper to deliver additional structure and stability.

These features work together to provide a supportive and comfortable running experience, particularly for those needing extra stability from their shoes.

Pros and Cons



As with other Brooks shoes, this model uses the brand’s GuideRails technology to prevent excessive movement and provide better foot support.

At 297g for the average size, these shoes are a little heavier than the typical design. It can be off-putting for those used to a lighter product.

The high-quality materials and construction make these shoes durable for long-term use.

The sole is a little stiff, which can be detrimental to those who want or need more flexibility in their ride.

This design uses engineered mesh for the upper, ensuring excellent airflow during movement to keep your feet comfortable when running.

To reach the highest levels of comfort, it takes some extra time to manage the break-in period with these shoes.

The cushioning and design help facilitate smooth transitions during most workout sessions, even when they are intense.

Brooks offers running shoes with similar technologies and features at a lower price point than the Glycerin GTS series.

It delivers a wider toe box than other running shoes, reducing pressure on the foot and allowing for more natural movement.

There is a lack of bounce or response to the stride when running in these shoes, emphasising comfort more than excitement.

How it Compares to Previous Models

What stands out to me with the 21s is the extra width in the toe box and improvements to the bulkiness of the overall design. It looks sleek and robust, which is a consistent update Brooks offers within this series.

The cushioning and design help facilitate smooth transitions during runs. The 21s provide exceptional balance, improving the training session.

Brooks has fine-tuned the outsole for the Glycerin GTS 21 to have more grip on different surfaces, allowing you to walk or run in various conditions. This feature combines with upgrades to the engineered mesh to give you flexibility without sacrificing stability with each step. 

The GuideRails in the 21s are more integrated than before, supporting a more natural stride. This technology is less intrusive than before while providing practical support levels, especially if you deal with up to moderate levels of overpronation. 

What It Is Like to Wear the Brooks Glycerin GTS 21

The approach Brooks took with this shoe is that if something is working, don’t try to change it. That benefits the runner who wants to do extended training sessions. I love how stable the GuideRails make the product, even though overpronation isn’t an issue for me personally.

Beyond the biomechanical focus, I do like how the drop in the shoe gives you a quick front-to-back transition that stays centred. You get stability that doesn't require you to think twice about it.

The 2mm of extra padding with the cushioning is a nice addition. It takes some of the strike away as an impact runner without feeling like your foot is getting covered by a pillow. My feet sank into the OrthoLite sock liner, providing an airy fit. As I started my run, the engineered mesh upper allowed for a comfortable, breathable experience, while the GuideRails technology offered excellent support. It kept my stride aligned, even when fatigue crept into the picture.

With that said, the 21s are noticeably softer than the other Brooks models or the previous iterations of this design. Although the heat can build in these shoes, the breathability of the mesh offer does an excellent job of dealing with that issue without too much fuss.

Looking at things I might change for these shoes, two items stand out immediately. I’d like them to be a little lighter to take some extra stress off the body, and it would be nice to have a lower drop. That takes nothing away from what the 21s accomplish for runners today.

The outsole's traction impressed me, providing grip that felt secure, even on slick surfaces. You feel confident with them on.

You can certainly build up to the experience of running in the 21s without an issue. They’re definitely an excellent choice for long runs with their stability and comfort. I’d recommend giving yourself two or three weeks to get used to the experience before pushing it. Otherwise, you’ll feel it in the morning.

I do appreciate the extra room in the toe box. It feels more natural to run because the outer shell isn’t constricting the foot in an unusual way. The transition zone between the heel and forefoot provided a smooth heel-to-toe roll, making each step feel like a natural continuation of the previous one.

I think the best way to describe the Brooks Glycerin GTS 21 is that it is a daily trainer that runs with firmness while providing a modest level of cushioning. It quickly became a dependable companion that I enjoyed using for various runs and training sessions.

Is it a Great Shoe to Wear?

When slipping on a pair of 21s, you’ll feel like the cushioning and support is the perfect structure to get you outside and training again. Even if you prefer a treadmill or a neighbourhood walk, the response from this design keeps your foot snug and secure with each stride.

I appreciate how responsive the Brooks Glycerin GTS 21 is, even with the extra cushioning. It feels plush without being overwhelming while delivering enough firmness to feel the steps in positive ways.

Try the Glycerin GTS 21 today like I did, and you’ll notice the difference with each training session.