I’ve been lacing up running shoes for years, chasing miles on trails, roads, and treadmills. When it came time to pick my next pair, I found myself torn between the Brooks Glycerin and its sleek cousin, the Glycerin StealthFit.
Both promise comfort and performance, but which one suits my stride? In this article, I’ll break down the key differences, weigh the pros and cons, and share my experience testing these shoes.
Whether you’re a seasoned runner or just starting, you’ll find insights to help you choose the right pair for your journey.
A Brief Comparison Table
| Feature | Brooks Glycerin (Standard) | Brooks Glycerin StealthFit |
| Upper Design | Engineered mesh, breathable, traditional fit | Knit, sock-like, adaptive stretch/compression |
| Cushioning | DNA LOFT v3, plush, 2mm more in Glycerin 21 | DNA LOFT v3, slightly firmer feel |
| Weight (Men’s US 9) | 10.3 oz (Glycerin 20), 9.8 oz (Glycerin 21) | 9.9 oz (StealthFit 20), 8.7 oz (StealthFit 21) |
| Heel-to-Toe Drop | 10 mm | 10 mm |
| Toebox Width | Wider, ~99 mm (Glycerin 21) | Narrower, ~95.3 mm (StealthFit 21) |
| Breathability | High, open mesh | Moderate, limited by knit upper |
| Fit | Roomy, accommodates wide feet | Snug, best for narrow to normal feet |
| Stability | Wide platform, optional GTS GuideRails | Slightly less stable, GTS available |
| Best For | Long runs, wide feet, breathability | Sleek fit, daily runs, narrower feet |
| Price | $160 | $160 |
Unboxing The Glycerin And StealthFit
When I pulled the Brooks Glycerin 21 out of its box, it felt like unwrapping a reliable old friend.
The classic engineered mesh upper looked airy, and the shoe had a reassuring heft—10.3 ounces for the Glycerin 20, dropping to 9.8 ounces in the 21.
The cushioning screamed plush comfort, and I couldn’t wait to test it on a long run.
Then came the Glycerin StealthFit 21, lighter at 8.7 ounces, with a sleek, sock-like knit upper that hugged my foot like a glove.
It felt modern, almost futuristic, but I wondered if that snug fit would hold up over miles.
The Glycerin’s traditional design, with its roomy toebox and padded collar, felt instantly familiar. I slipped it on, and my toes had room to wiggle—perfect for my slightly wider feet.
The StealthFit, though, was a different story. Its compressive knit upper gripped my foot tightly, especially around the midfoot. It wasn’t uncomfortable, but it felt like it was designed for someone with narrower feet. I laced both up, eager to hit the pavement and see how they’d perform.
Cushioning & Ride Comparison of Brooks Glycerin And StealthFit
Both the Glycerin and StealthFit use Brooks’ nitrogen-infused DNA LOFT v3 foam, but the experience isn’t identical. The Glycerin 21 boasts an extra 2mm of stack height (38mm heel, 28mm forefoot), making it the plushest in Brooks’ lineup.
When I ran in it, the cushioning felt like landing on a cloud—soft yet supportive, with just enough bounce to keep my legs fresh after 10 miles. It’s a dream for heel strikers like me, thanks to the 10mm drop that encourages smooth heel-to-toe transitions.
The StealthFit 21, while still cushioned, feels slightly firmer. Its midsole is marginally less plush, which I noticed on longer runs. It’s not a dealbreaker, but it lacks that sink-in softness of the standard Glycerin. However, the StealthFit’s responsiveness surprised me.
On a 5-mile tempo run, it felt snappier, almost urging me to pick up the pace. The trade-off? It’s not as forgiving on ultra-long runs, where the Glycerin’s extra cushioning shines.
I tested both on a mix of surfaces—concrete, asphalt, and light gravel. The Glycerin’s wider platform (about 3mm wider than the StealthFit) provided a stable base, especially on uneven terrain.
The StealthFit, with its narrower profile, felt less grounded during sharp turns but excelled on straightaways. If you’re a runner who loves a cushioned, stable ride for marathons or recovery runs, the Glycerin is your go-to. For daily training with a touch of speed, the StealthFit holds its own.
Upper Design: Comfort Meets Style
The upper is where these shoes diverge most dramatically.
The Glycerin’s engineered mesh is a breath of fresh air—literally.
On a hot summer run, my feet stayed cool, thanks to the open weave.
The toebox, measuring around 99mm at its widest, gave my toes plenty of room to splay, which is a godsend for long runs when feet swell.
The padded collar and tongue added a plush feel, though I noticed the heel padding pushes the foot slightly forward, making the fit feel a tad shorter than the Glycerin 20.
The StealthFit’s knit upper, dubbed “FitKnit,” is a game-changer for style-conscious runners. It’s sleek, seamless, and molds to your foot like a second skin. I loved the sock-like fit at first—it felt like the shoe was part of my foot. But after a few miles, I noticed less ventilation.
My feet got warmer than in the Glycerin, and the toebox (95.3mm wide) felt snugger, which might be an issue for runners with wide feet. The external lacing system, a hallmark of the StealthFit, eliminates tongue pressure, which was a relief for the top of my foot.
One downside? The StealthFit’s knit upper can feel less durable. After 50 miles, I noticed slight wear near the toebox, whereas the Glycerin’s mesh held up flawlessly. If breathability and durability are your priorities, the Glycerin wins. If you crave a snug, stylish fit, the StealthFit delivers.
Fit and Sizing: Finding the Sweet Spot
Fit is personal, and these shoes cater to different foot shapes. The Glycerin is true-to-size with a roomy fit, especially in the toebox. I wear a men’s US 9, and the Glycerin 21 felt perfect, with enough space for my toes to move without feeling sloppy.
Brooks offers wide (2E) and narrow options, making it versatile for various foot widths. My high arches appreciated the supportive insole (5.2mm thick), and the heel lockdown was impeccable, thanks to the stiff counter.
The StealthFit, however, is a different beast. Its “skinny jean” fit, as Brooks describes it, is snug through the midfoot and heel. I found it true-to-size but less forgiving for wide feet. The narrower toebox (0.6mm less than the Glycerin) felt restrictive after 8 miles, especially as my feet swelled.
If you have narrow to normal feet, the StealthFit’s compressive fit feels secure and adaptive. For wide-footed runners, it might lead to hotspots or discomfort on longer runs.
I also tested the StealthFit with custom orthotics, and it accommodated them well, though the snug fit left less room than the Glycerin. If you need extra space or prefer a relaxed fit, stick with the standard Glycerin. If you love a glove-like feel, the StealthFit is your match.
Stability & Support Comparison of Brooks Glycerin And StealthFit
Both shoes offer solid stability, but the Glycerin edges out slightly. Its wider platform and optional GuideRails (in the GTS version) make it a favorite for overpronators or supinators like me.
The GuideRails act like bumpers, guiding my foot to prevent excessive rolling. Even without GTS, the Glycerin’s broad base and firm midsole kept me stable on long runs, especially on gravel trails.
The StealthFit, while stable, feels less planted due to its narrower platform. The GTS version helps, but it’s not as supportive as the Glycerin GTS. I noticed slight wobbling during sharp turns, particularly in wet conditions.
The StealthFit’s flexibility (30.8N to bend to 90 degrees) is a plus for natural foot movement, but it stiffens slightly in cold weather (4.9% stiffer), which I felt on a chilly 6-mile run.
For runners needing extra support, the Glycerin GTS is the better choice. If you’re a neutral runner with a steady gait, the StealthFit’s lighter weight and flexibility might suit you better.
Outsole and Durability: Traction That Lasts
The Glycerin 21 introduces Brooks’ RoadTack rubber outsole, a mix of rubber and recycled silica. It’s grippy on wet and dry surfaces, scoring 0.50 on a SATRA TM144 grip test. I ran through light rain, and the Glycerin held firm on slick sidewalks.
The outsole’s segmented design, with flex grooves, enhances transitions, though it’s less durable than the Glycerin 20’s thicker rubber coverage. After 100 miles, I saw minor wear in high-impact zones, but nothing alarming.
The StealthFit 21 uses the same RoadTack outsole, with slight variations in rubber placement. It performs equally well on wet concrete but shows similar wear patterns. Both shoes are built for 350-600 miles, with the Glycerin GTS 20 claiming up to 600 miles thanks to its robust construction.
I found the Glycerin’s outsole slightly more durable due to its thicker rubber pads, but the StealthFit’s lighter design didn’t sacrifice much in longevity.
Breathability: Keeping Your Feet Cool
Breathability is a big differentiator.
The Glycerin’s engineered mesh upper is a champ in hot weather.
During a 90°F run, my feet stayed relatively cool, and the open weave allowed air to flow freely.
The StealthFit, however, struggles here. Its knit upper, while stylish, traps heat.
Tests with a smoke-pumping machine and light confirmed poor ventilation, with small toebox holes hindered by an inner knit layer.
On warm runs, my feet felt noticeably warmer in the StealthFit.
If you run in hot climates or prioritize airflow, the Glycerin is the clear winner. For cooler weather or indoor workouts, the StealthFit’s reduced breathability is less of an issue.
Weight and Versatility: Balancing Comfort and Speed
The Glycerin 21 (9.8 oz for men’s US 9) is lighter than its predecessor (10.3 oz), but it’s still a touch heavier than the StealthFit 21 (8.7 oz). The weight difference is noticeable on faster runs— the StealthFit feels nimbler, making it a versatile daily trainer.
I used it for 5K runs and tempo workouts, and it kept up without feeling clunky.
The Glycerin, while not sluggish, is better suited for easy paces and long distances. Its extra cushioning absorbs shock, making it ideal for half-marathons or marathons.
I ran 15 miles in the Glycerin 21, and my knees felt fresh, whereas the StealthFit started to feel firm after 10 miles. If speed is your goal, the StealthFit has an edge; for endurance, the Glycerin reigns supreme.
Pros And Cons of Brooks Glycerin And StealthFit
Brooks Glycerin Pros
- Plush Cushioning: Extra 2mm of DNA LOFT v3 foam makes it ideal for long runs.
- Breathable Upper: Engineered mesh keeps feet cool in hot conditions.
- Roomy Fit: Wide toebox (99mm) suits broader feet and accommodates swelling.
- Stable Platform: Wide base and optional GuideRails enhance support.
- Durable Outsole: RoadTack rubber offers solid grip and longevity.
Brooks Glycerin Cons
- Heavier Weight: At 9.8 oz, it’s not ideal for speedwork.
- Shorter Fit: Extra heel padding can push the foot forward.
- Less Stylish: Traditional design may not turn heads.
Brooks Glycerin StealthFit Pros
- Lightweight Design: At 8.7 oz, it’s nimbler for daily training.
- Snug, Stylish Fit: Sock-like knit upper feels modern and secure.
- Responsive Ride: Firmer midsole adds a touch of speed.
- External Lacing: Eliminates tongue pressure for added comfort.
- Versatile Use: Great for daily runs, tempo work, and casual wear.
Brooks Glycerin StealthFit Cons
- Poor Breathability: Knit upper traps heat, less ideal for hot runs.
- Narrow Fit: 95.3mm toebox may cause discomfort for wide feet.
- Less Stable: Narrower platform feels less grounded on turns.
- Durability Concerns: Knit upper shows wear faster than mesh.
Who Should Choose Which?
As I logged miles in both shoes, I realized they cater to different runners. The Glycerin is a marathoner’s dream—plush, stable, and breathable, it’s built for long, easy runs.
If you have wide feet, overpronate, or run in hot climates, the Glycerin (or GTS version) is your best bet. Its roomy fit and durable outsole make it a reliable workhorse.
The StealthFit, with its sleek design and lighter weight, is perfect for runners who want a snug, responsive shoe for daily training or shorter, faster runs. It’s less suited for wide feet or ultra-long distances but shines for those with narrow to normal feet who value style and versatility.
If you’re torn, consider your foot shape and running goals.
Which One Won My Heart?
After weeks of testing, I lean toward the Glycerin 21. Its plush cushioning and breathable upper made my long runs a joy, and the wide fit suited my feet perfectly.
The StealthFit impressed me with its sleek design and responsiveness, but the snug toebox and warmth were drawbacks for my longer sessions. That said, I’d happily wear the StealthFit for shorter runs or gym workouts.
Your choice depends on what you value most. Want supreme comfort for endless miles? Go Glycerin. Craving a modern, snug fit with a touch of speed? StealthFit’s your pick. Either way, Brooks delivers quality that’s hard to beat.
Also Read: Differences Between Hoka Transport And Clifton 9 Shoes.
Frequently Asked Questions (FAQ)
The Glycerin features a breathable mesh upper, wider toebox (99mm), and plusher cushioning, ideal for long runs and wide feet. The StealthFit has a snug, knit upper (95.3mm toebox), lighter weight (8.7 oz vs. 9.8 oz), and a firmer, more responsive ride, suited for daily training and narrower feet.
StealthFit is Brooks’ sock-like, knit upper design that offers a close, adaptive fit with stretch and compression. It features external lacing to reduce pressure and a sleeker look, but it’s less breathable and better for narrow to normal feet.
Yes, the StealthFit 21 is comfortable for walking, with a cushioned midsole and secure fit. However, its narrower toebox and limited breathability make it less ideal for long walks compared to the standard Glycerin, which offers more room and airflow.
Conclusion: Your Run, Your Choice
You’re standing at the crossroads of comfort and style, and both the Brooks Glycerin and StealthFit are calling your name. I’ve run miles in both, felt the plush embrace of the Glycerin’s cushioning, and marveled at the StealthFit’s sleek grip. If you’re chasing long, easy runs with room to breathe, the Glycerin’s your trusty companion.
If you want a lighter, snug shoe that adds a dash of speed, the StealthFit won’t disappoint. Try them on, listen to your feet, and let your stride decide. Happy running!
