ShoesBrooksGlycerin Stealthfit 21

Brooks

Brooks Glycerin Stealthfit 21

Brooks Glycerin Stealthfit 21. 36.9mm stack, 257g. Retailer specs verified on Running Warehouse.

PR Run Verified
Soft trailsLong ultrasDaily training

PR Run scores

Grip3/5
Cushion5/5
Protection2/5
Durability3/5
Versatility3/5

PR Run derived fit scores

79Great

100-miler readiness

Will this shoe survive a hundred-mile night? 36.9 mm stack, cushion 5/5

90Elite

Descent tolerance

Does it save your toenails on long descents? 26.4 mm forefoot, heel counter 3/5

100Elite

Swelling room

Room to grow when your feet swell? 26.5 mm toebox height

73Great

Grit resistance

Does dust stay outside the shoe? 2 BR breathability

22Weak

Hot-day comfort

How well does it breathe in heat? 2 BR / ?% drying

50Solid

Achilles-friendly

Kind to a cranky achilles? 10.5 mm drop, heel counter 3/5

Full specs

Drop

10.5 mm

Heel stack

36.9 mm

Forefoot stack

26.4 mm

Weight

257 g

Plate

No

Waterproof

No

Lab measurements

MeasurementValue
Traction (CoF)0.50
Breathability2 BR
Flexibility13.1 N
Heel counter3/5
Energy return52.0 %
Shock absorption125 SA
Outsole thickness3.2 mm
Tongue padding2.1 mm
Insole removableYes
Insole thickness5.2 mm
Reflective elementsNo

Lab numbers from RunRepeat. Sources.

Fit intelligence

Toebox width

Narrow toebox (72.8 mm vs 96 mm median)

Toebox height

Slightly tall (26.5 mm vs 25 mm median)

True to size.

Fit numbers from the lab. Swell guidance: foot care.

Questions before you race

Is the Brooks Glycerin Stealthfit 21 good for 100-mile races?

Great. 36.9 mm stack, cushion 5/5. 100-miler readiness score 79/100.

Does the Brooks Glycerin Stealthfit 21 fit wide feet?

No. Toebox is 72.8 mm which is narrow. Look elsewhere if you need width.

What is the drop on the Brooks Glycerin Stealthfit 21?

10.5 mm, with a 36.9 mm heel stack and 26.4 mm forefoot.

Is the Brooks Glycerin Stealthfit 21 good on wet rock?

Traction coefficient of friction on wet lab surface: 0.50. Solid grip on wet rock.

Manufacturer specs

New lab data on soft trails shoes, once a month.

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Image: Brooks product photo

Specs: retailer. Verified Sep 2, 2026.

Report inaccurate data: hi@pr.run. Data sources.

Brooks Glycerin Stealthfit 21 Review, Specs, and Fit (2026) | PR Run