Brooks Glycerin 23 review

We tested the Brooks Glycerin 23 and concluded that:

• Runners looking for a premium daily trainer with high comfort and strong durability will enjoy this model.
• Those who avoided the Glycerin before due to the high drop will find this version more balanced.
• Owners of previous versions who want a safe upgrade will feel right at home, as it keeps the same Glycerin DNA.
• Casual runners wanting one shoe for easy runs and daily wear, and who have a higher budget, will find it a great fit. It looks better than ever too!

Runners that dislike heavy shoes will not enjoy the Glycerin 23. We found in the lab that its weight is too high, and we believe lighter options like the Mizuno Neo Zen 2 or New Balance 1080 v15 can be better choices for you.

The ride also lacks a lively bounce, with a more comfort-first feel instead. We think it’s not the best option for runners seeking energy return, and we recommend the Adidas Ultraboost 5 or 5X for a more responsive experience.

After the full revamp of the Glycerin 22, we did not expect major changes, so a similar shock absorption result made sense here. Once we finished testing the Glycerin 23, we recorded 140 SA in the heel and 116 SA in the forefoot, a small but welcome 5% improvement over its predecessor.

The midsole still uses the same DNA Tuned compound, which already fell short for us in terms of bounce. So, as expected, energy return remains below average, reaching only 54.1% in the heel and 57.7% in the forefoot.

While this may not be an issue for runners using the shoe for easy weekly miles without performance goals, we still believe that at this price point Brooks should offer a foam that delivers over 65% in this test.

The Glycerin 23 reflects the current trend of daily trainers moving close to 40 mm of stack height.

In this update, we measured 37.2 mm, which keeps the shoe just below the maximalist category while offering better versatility and a slightly improved connection to the ground.

The forefoot also approaches the 30 mm mark, landing at 29.0 mm, which is slightly higher than the previous version. Therefore, there is plenty of foam here as well for both midfoot and forefoot strikers.

Brooks followed the same approach as in the Adrenaline GTS 25, reducing it by 2 mm, so it now features an official 8 mm drop instead of 10 mm.

In our lab, we measured a minimal difference at 8.2 mm, which makes this shoe feel more balanced for all footstrikes rather than mainly focused on heel strikers. We think that this is a positive change.

As we noted earlier when discussing the disappointing energy return, this is the same DNA Tuned foam from last year. For that reason, it keeps the dual-density setup, but Brooks uses a custom process that bonds both layers without glue.

The main foam layer runs through the entire forefoot and midfoot, plus the top part of the heel. This helps explain why the shoe feels softer than previous Glycerin models, measuring only 29.2 AC in our tests.

A firmer foam layer is present only in the lower part of the heel, measuring a higher 34.8 AC. However, the overall ride still feels noticeably softer than the average shoe.

The Brooks Glycerin 23 has a moderate amount of curvature in both the forefoot and heel, but nothing that feels forced or unusual underfoot. This makes it a great option for easy runs and daily use, as heavily rockered shoes can feel awkward in those situations.

However, our precise measurements showed that the toes now sit slightly higher 5 mm higher, which is not surprising given the new, lower drop. Brooks needed to offset that change, and they did.

The fit of the Glycerin has always leaned toward a conservative approach. That means accommodating as many feet as possible and staying close to average in our measurements.

To confirm this, we recreated the interior of the shoe using our custom gel method. Once it cooled, our first measurement came in at 96.1 mm, more or less around the current average.

The toebox width also sits close to the lab average at 73.9 mm, offering solid comfort and working well for most feet. As usual with the Glycerin, Brooks also offers wide sizes, although not in every market.

One area that changes is the toebox height.

We found this to be a potential issue in version 22 at only 23.6 mm, but Brooks addressed it by increasing it to a more reasonable 27.7 mm here, reducing pressure on the toes.

Some modern daily trainers are performing very well in traction, but the Brooks Glycerin 23 does not quite reach that crazy-good level.

That said, we found that a 0.57 score is still good enough to deliver solid grip even in rainy conditions, and it also marks a clear improvement from the 0.44 of its predecessor. And with Brooks raising the price of the shoe, delivering some improvements is clearly needed.

The outsole has plenty of rubber coverage and improves on the previous version, which was already good.

It now features more defined horizontal flex grooves and two new longitudinal ones that were not present before, helping maintain a similar level of stiffness despite having slightly more foam up front due to the reduced drop.

The stiffness result is practically the same as last year, reaching 15.2N to bend the shoe to 30 degrees. It is another result that does not stand out and reflects very well the balanced character of the Glycerin 23.

Where Brooks clearly struggles is weight—and it is not just this model. Other lines like the Ghost or the Adrenaline also trend heavier than most competitors.

Here we measured 10.7 oz or 303g, and we can say that the Glycerin 23 feels heavy on foot. Brooks prioritises outsole durability and upper comfort, but those choices work against reducing weight and limit overall agility.

Shoes with knit-based uppers that focus heavily on comfort often gain weight and lose some breathability, because air can get trapped inside the plush materials that wrap the foot.

To check this, we ran our usual tests, starting with the smoke challenge to see how much air can escape from the shoe. We gave the Glycerin 23 a 3/5.

While the knit upper has many ventilation holes in the top layer, a thick secondary layer limits airflow. The tongue follows a similar design, helping some airflow through the instep.

Looking at the upper under our digital microscope made it clear that Brooks focused on comfort and support, with breathability playing a smaller role. The build quality looks very good.

Another area where Brooks clearly focused is comfort. The padding in the heel and tongue is extremely generous and plush, one of the most impressive we've ever seen in a daily trainer.

The Glycerin 23 is clearly aimed at neutral runners, as it does not include GTS in the name like Brooks models designed for support, and that is reflected in its design. We do not recommend it for those with stability needs at all.

That said, it's plenty stable and a safe option for neutral runners.

Thanks to the outsole design and a still reasonable stack height, we found that the Glycerin 23 maintains moderate torsional rigidity and delivers a balanced feel in that sense. In other words, it is not overly flexible, but also far from uncomfortable for daily use or easy runs.

Brooks used a moderately rigid heel counter that we rated at 4/5. This is not uncommon for the brand, as they often do this in the Glycerin or Adrenaline series, likely because they offset the added rigidity with the ultra-plush padding we mentioned earlier.

It is no secret that running shoes are getting taller, but also much wider. That is clearly reflected in the Glycerin 23, as we measured a huge 120.4 mm, something that only a few years ago would have been more common in stability shoes. This is simply the new normal now.

With Brooks making the Glycerin softer each year, we think this was likely a necessary design change. The shoe still feels good, but do not expect it to behave as agile as models from five years ago.

The heel expands from 89.7 mm in version 22 to a broad 98.6 mm in version 23. As a result, you can expect more stable heel landings in this update.

Knit-based uppers sometimes struggle with toebox durability, but that is not the case with the Glycerin 23. The material used by Brooks feels aligned with the premium price of the shoe and delivers excellent comfort along with a solid 3 out of 5 durability score.

That combination is not easy to find!

The heel padding also performed well, earning a 4/5 score. It surpasses the current lab average and removes any concerns about long-term wear.

To complete the trifecta of durability tests, we powered up the Dremel and tested the outsole. The rubber performed very well, as we measured only 0.7 mm of wear and were left more than satisfied.

Brooks tends to use thick outsoles in its daily trainers, and that is clear again here.

This 3.3 mm rubber layer adds an obvious weight penalty compared to some competitors, but those looking for a durability-first daily trainer will appreciate it.

We used our digital callipers to measure the insole thickness, and it came in at 4.4 mm. Nothing unusual here.

The insole can be removed, and with the improved vertical clearance in the toebox, using a slightly thicker one is also an option.

The DNA Tuned midsole looks great and feels comfortable, but it is still an EVA-based foam that changes too much in cold temperatures. We found that it lost 33% of its softness after 20 minutes in our freezer, which is a poor result.

It is always nice to find reflective elements, even if they are just two small pieces in the heel.

Even the laces are clearly tuned for comfort, as Brooks moves away from thin flat laces and uses thicker ones with a lightly padded feel. This choice adds some weight, showing again that reducing grammes is not a priority here.

We also found that the tongue delivers outstanding comfort, using a single piece of low-density, soft foam that reaches 9.0 mm in thickness. The added perforations improve airflow, and the green secondary layer gives it a striking look.

However, we found it disappointing that the tongue is not gusseted given the high price of the shoe. It is not surprising, as Brooks has been following this approach in several recent models we tested, but it still feels like a miss for us.

The heel features a finger-loop tab that takes advantage of the knit material and feels somewhat similar to recent ASICS designs like the Gel Nimbus 28. As they say, imitation is a form of flattery...

The Glycerin 23 brings some positive updates, but it also comes with a price increase. While it is true that this model has been more affordable than some competitors in recent years, we think a real tech upgrade is needed to justify the higher cost in this version.