Height increase: ~3.5 cm (1.4 in) – a tall, cushioned Gore‑Tex trail shoe (but notably heavy).
Why People Ask This Question
Nike’s ACG (All Conditions Gear) line is built for rugged trail use and has a strong style following. The Mountain Fly SE is a waterproof trail runner (with a GORE-TEX upper) designed for hikers and outdoor enthusiasts. Its chunky Nike React midsole gives it a lofty, maximalist look, so many fans ask “how tall is this?” For context, a typical running shoe has about 25–35 mm of heel stack, so the Fly SE’s elevated sole naturally makes people wonder exactly how much height it adds.
Official Stack Height vs. Real-World Measurement
Nike’s product pages don’t publish a stack height for the Mountain Fly SE, so there’s no official figure to quote. In practice, reported “stack” numbers often come from teardown guides or leaked specs, and can differ from actual lift. (For example, lab tests have found running-shoe drops measuring a few millimetres higher than the brand’s spec.) In other words, nominal midsoles are given uncompressed, but your feet compress the foam in use. So without a definitive Nike spec, we rely on measurement to find the real lift.
How We Measured
We measured a US 9 (UK 9) sample of the Mountain Fly SE using a digital vernier caliper (resolution ±0.2 mm). Following official guidelines, the caliper was placed at the centreline of the heel (about 12% of foot length from the back) to avoid any edge or rocker effects. The shoe was laid flat with the factory insole in place, and height was read from the top of the footbed to the ground. As usual, we note that sizing has only a small effect (different sizes of the same model typically vary by ~1–2 mm), and any two pairs can differ by about ±2 mm due to manufacturing tolerances.
Exact Height Increase
Our measurement: ~3.5 cm (≈1.4 in) of lift at the heel. For reference, independent lab tests found the Mountain Fly 2 Low’s heel stack to be 35.5 mm. The Fly SE’s measured height is on the same order – roughly 3.5 cm. This is slightly less than the full uncompressed thickness of the foam, because Nike React is soft and compresses under weight. In short, expect about 3.5 cm (1.4 in) of added height in everyday wear.
On-Foot Feel & Gait Changes
The Mountain Fly SE feels very cushioned and supportive on foot. Nike markets it with a GORE-TEX upper and a React foam midsole for a “smooth, responsive ride”. In practice you’ll experience a soft, plush underfoot sensation and a surprisingly stable platform. RunRepeat’s testers noted the Mountain Fly 2 (a similar ACG model) felt “safe and sound” even on uneven terrain, and gave it a perfect 5/5 torsional rigidity (i.e. it resists twisting). On the flip side, any very thick midsole slightly alters your posture: research on raised heels shows increased heel lift forces the foot into more plantar flexion, which tends to increase knee bend and lumbar arch. In other words, the higher heel shifts your centre of gravity forward. Also, thicker, softer shoes have been found to reduce proprioception and balance in a dose-dependent way. In everyday terms, you get a plush, lofty ride and a broad base (great for absorbing shock), but you’ll also notice a little extra “rocker” feeling and weight underfoot. The shoe’s wide sole (even wider than many trainers) helps keep you stable, so most wearers just feel cushioned and confident on long walks or hikes. Just be aware it’s heavier and “springier” than a slim trainer, so fast sprints may feel a bit sluggish.
Comparison Chart
For context, below is a comparison of heel lift for similar shoes. The Nike ACG Fly SE’s ~3.5 cm boost is comparable to other high-stack trainers: for example, the Mountain Fly 2 Low measures about 3.55 cm, Hoka Gaviota 4 about 3.66 cm, and Hoka Bondi 8 about 3.62 cm. By contrast, a standard Nike Pegasus (heel stack ~30.2 mm) adds roughly 3.0 cm. The chart below summarizes these figures:
| Shoe Model | Height Gain |
|---|---|
| Nike ACG Mountain Fly SE (this shoe) | ~3.5 cm (1.4 in) |
| Nike ACG Mountain Fly 2 Low (2024) | ~3.6 cm (1.4 in) |
| Hoka Gaviota 4 | ~3.7 cm (1.5 in) |
| Hoka Bondi 8 | ~3.6 cm (1.4 in) |
| Nike Pegasus 40 (regular trainer) | ~3.0 cm (1.2 in) |
Styling & Sizing Tips
Styling-wise, the Mountain Fly SE has an “outdoorsy” look. It pairs well with cargo or jogger pants (especially tapered or cropped at the ankle) for a rugged streetwear vibe. Earthy tones and technical fabrics complement its hiking-boot aesthetic. You can also wear it with shorts or roll-up chinos to show off the thick sole. Since it’s a high-cut trail sneaker, wearers often size it like a boot in their usual Nike size – it’s listed as a regular fit. In practice, we recommend ordering your normal Nike size. The shoe’s single-bootie construction can feel snug, so if you have particularly wide feet or wear thick socks, you might consider a half-size up for comfort. Overall, there’s no need to go up or down unless you’re between sizes – most find it true to size as indicated.
Pros, Cons & Ideal Use Cases
- Pros: Thick, springy React cushioning for comfort; waterproof GORE‑Tex upper; rugged traction and wide base for stability; distinctive techy style.
- Cons: Fairly heavy (~431g) and bulky; bulky looks may not suit everyone; higher price point; some may find it too warm in hot weather.
- Ideal for: Trail running, hiking and wet-weather walks; anyone wanting a comfortable, height-boosting shoe for the outdoors; city commuters seeking all-weather grip and max cushioning.
FAQ
Q: Can I use my own custom insoles or orthotics with these shoes?
A: Yes. Like most performance sneakers, the Fly SE has a removable insole. It’s explicitly marked “orthotic friendly” in specifications, so you can swap in custom insoles or orthotics if needed.
Q: How durable is the cushioning (React foam) over time?
A: Nike React is quite durable for a running shoe midsole. In practice you can expect on the order of 100–150 miles of use before it compresses significantly. This is roughly double what standard EVA (e.g. older Hoka foam) might handle. In short, it should hold up for many miles of hiking or walking before the shoe feels noticeably “bottomed out.”
Q: Are these shoes very heavy?
A: They are on the heavier side. In lab tests, a Mountain Fly 2 Low (similar construction) came in at about 431 g (15.2 oz) for a men’s UK9. The Fly SE has comparable heft due to its beefy sole and Gore‑Tex lining. This extra weight means you’ll definitely feel them on long climbs or runs – you’ll trade off nimbleness for durability and cushion.
Conclusion
The Nike Mountain Fly SE adds roughly 3.5 cm (1.4 in) of height, giving you a noticeably higher stance than a standard trainer. Its thick React midsole and waterproof GORE‑Tex upper deliver a very cushioned, supportive ride—ideal for hiking or casual wear—though the shoe is noticeably weighty. Overall, it’s a rugged, high-stack trail sneaker: great if you want extra height and comfort on trails, but probably more than you’d need for speedwork. For more on sneaker stack heights and boost, check out HowMuchHeight.com, where you’ll find measurements and reviews for many other models.
