Brooks Glycerin Flex running shoe review – opinion, price, comparison, who it’s recommended for

Brooks Glycerin Flex running shoe upper

The Brooks Glycerin Flex running shoe upper is made from a knit mesh material. Building a running shoe with a knit upper is always a bit riskier, because compared to more structured mesh uppers, a knit upper gives you a lot of freedom and flexibility, but it usually holds the foot less securely as well. Fortunately, that is not the case with the Glycerin Flex, because it has extra padding around the heel, and the soft, thick laces can be tightened really well. The upper is comfortable, yet still gives you freedom. Thanks to the large ventilation holes, breathability is good. The tongue is medium-thick, more flexible than average, protects the instep well, but it is not gusseted. Since it is wider, it hardly shifts sideways while running. The heel collar has a rear counter and thicker padding, so it is not only comfortable but also holds the foot well. Lengthwise, the shoe fits true to size. It is a little narrower than average, but because it stretches well, it can still be comfortable for wider feet too. The insole is not glued in, so you can replace it. The shoe’s design is also hard to ignore. The shape of the upper is classic, but the green dots next to the holes (pink on the women’s version) create an effect as if a green light were glowing from inside. This continues into the midsole too, as the white foam is colored in a way that makes it look like it is being lit from within by a green glow.

Brooks Glycerin Flex running shoe midsole

The Brooks Glycerin Flex running shoe midsole is made entirely from DNA Tuned foam, which is a nitrogen-infused EVA foam. What makes this foam special is that it contains nitrogen bubbles of different sizes: smaller bubbles in the forefoot and larger ones in the heel. Thanks to this difference, the forefoot feels more dynamic, while the heel offers better impact protection. In practice, it is a dual-density foam, but the two parts do not have separate names like in most running shoes whose midsoles are made from two foams with different densities. The real standout feature of the midsole is the FlexZone construction, which means there are deep longitudinal and crosswise cutouts in the midsole, making it very flexible. You can twist the shoe and bend it easily. This solution makes the ride feel very natural, and your foot can move completely freely in it. I really like using it not only for running but also in everyday life, because it is light, flexible, and almost feels like there is nothing on your foot. While running, I felt the benefits of this less beyond the comfort, but it still delivers a very unique ride. The midsole is not especially tall. It has some bounce, but nothing exceptional. Because it is not overly high and it is flexible, ground feel is pronounced. You feel your own effort much more clearly, and less of what the shoe adds. That is a really good feeling, because it gives you feedback about your own abilities and power. Since I am sensitive to this, I was a little concerned about the shoe’s stability. Flexible, bendy midsoles usually tend to be weak in stability. That was not the case with the Brooks Glycerin Flex. I would not say the shoe has great stability, but I would not call it weak either. The midsole is not excessively high, and the flexible zones and separate segments are designed in a way that supports the inside of the forefoot well. The heel section is asymmetric too, with more support on the medial side. Thanks to these features, the shoe has above-average stability.

Brooks Glycerin Flex running shoe outsole

The Brooks Glycerin Flex running shoe outsole supports the segmentation of the midsole brilliantly and, with one exception, it is segmented in the same way as the midsole. The exception is on the inner forefoot, where the outsole connects two separate midsole sections, and this connection improves the shoe’s stability. The outsole is thicker than average and made from rubber that is slightly firmer than average. Its abrasion resistance is good, and because it is also thicker, durability is very good. On dry ground, the outsole grips very well, while on wet ground its traction is average, or just a touch below average.

What is it like to run in the Brooks Glycerin Flex running shoe?

The Brooks Glycerin Flex delivers a very unique experience. Its flexible midsole and lightweight upper give you a sense of freedom, which is further helped by its low weight. You feel your own power in it, rather than the shoe doing the work and helping you run. It offers strong ground feel and a natural ride.

Cushioning and midsole

Compared to today’s midsoles that often exceed 40 mm, the Brooks Glycerin Flex midsole is not tall, with “only” 36 mm in the heel. Accordingly, its cushioning is not especially high either; it can be described as average. The midsole has solid, average-level responsiveness, but the shoe cannot really be called fast or especially efficient over long efforts. Still, if you want to run freely at an easy or moderately brisk pace, even up to half marathon distance, it is perfectly suitable.

Stability and guidance

The Brooks Glycerin Flex midsole and outsole are heavily segmented, flexible, and pliable. As a result, its stability is not high, but it cannot be called weak either. In general, this kind of flexible platform tends to be less stable, but Brooks paid attention to counterbalancing that. One of the inner forefoot segments provides good support, and the heel is asymmetrical with a larger medial side, which also improves stability. The Glycerin Flex is a shoe built around a natural running feel, with less guidance, and that is exactly the point. There is no pronounced rocker in the midsole, and even if there were, the flexible midsole would not really hold it.

Upper and comfort

The Brooks Glycerin Flex running shoe upper is made from a flexible knit material. Apart from the heel collar, there are no reinforcements in it, so it is less structured, but because it uses a somewhat thicker material, foot hold is still good. Even though this knit upper is relatively thick, breathability is not bad thanks to the larger ventilation holes. The heel collar is padded, comfortable, and holds the heel well. The tongue is on the thinner side, but still adequately padded. The upper delivers freedom and comfort at the same time, which is a rare combination.

Foot strike and traction

The Brooks Glycerin Flex running shoe midsole is very flexible, guides the foot less, and while transitions are not especially fast, they are comfortable. Its drop is lower than average, which mainly supports landing more toward the forefoot. The outsole is thick and has deep grooves, so grip is good. This is further enhanced by the fact that the midsole sections can move independently, allowing the shoe to conform to the ground better than a running shoe with a more rigid midsole.

Pace and dynamics

The Brooks Glycerin Flex running shoe midsole has decent, average energy return. You can run a few faster sections in it, but fundamentally this is not a shoe built for sustained, long, fast runs. Because it gives such a natural ride, its special character really comes through more on light, relaxed runs where you want to enjoy running rather than tick off training tasks. It is lightweight, which makes it possible to pick up the pace, but this is not the shoe in which you will break your time records. Still, you can absolutely train and prepare for them in this shoe.

Long runs vs tempo vs training

The Brooks Glycerin Flex running shoe is not specifically designed for long runs, but it is comfortable enough for half marathon distances. It is not a racing shoe, because it does not have enough dynamism for that, but it is excellent for everyday training, including hybrid sessions combined with other sports.

Who is the Brooks Glycerin Flex running shoe recommended for – and who is it not for?

If you are looking for a neutral, lightweight, comfortable running shoe that delivers a natural ride, the Brooks Glycerin Flex running shoe can be a good choice. Because of its natural movement, it also works well for walking or for sports where running is only part of the activity. Breathability is good, so it is also a good option for the gym and can work well for HYROX training.

If you are specifically looking for a running shoe for long training sessions, if you want a fast, very dynamic running shoe, or if you need a highly stable shoe because you overpronate or supinate, then the Brooks Glycerin Flex may not be the best choice for you.

Brooks Glycerin Flex running shoe alternatives – comparison

Because the main standout feature and uniqueness of the Brooks Glycerin Flex running shoe is the high flexibility of its midsole, the most relevant alternatives are similarly flexible running shoes, even if they differ in other characteristics. Similar flexible running shoes include:

• The Adidas Adizero Adios 9, which has a lower-stack midsole but similar flexibility
• The Asics Noosa Tri 16, which has a similarly tall midsole, but is not quite as flexible
• The first version of the Mizuno Neo Zen, which is taller and not quite as flexible, but the upper is similar in many ways
• The New Balance FuelCell Rebel v4, which is more stable, wider, but also flexible and lightweight
• The Puma Velocity Nitro 4, which has a higher drop, but a similarly tall midsole that also sits on the more flexible side
• The Saucony Kinvara 16, which has a lower-stack midsole and a more locked-down upper, is more suited to short, faster runs, but is similarly flexible

Is there a difference between the men’s and women’s Brooks Glycerin Flex running shoe?

The official midsole dimensions of the women’s Brooks Glycerin Flex are identical to those of the men’s version: 36 mm in the heel and 30 mm under the toes. At the same time, the women’s Glycerin Flex is officially 31 grams lighter than the men’s version, but that is mainly because the women’s version is measured in size 29, while the men’s version is measured in size 42.5.