For trail runners and fastpackers who chase pace and minimal weight across mountain terrain, waterproof layers often feel like necessary burdens. That’s where the Montane Minimus Nano Pull-On Jacket stands out. Designed to be one of the lightest waterproof shells available—with a weight hovering around 100 grams—it’s built for speed-focused outdoor users who need emergency protection without bulk or bounce.
In this long-term test, we assess the Nano’s breathability, fit, waterproof performance, and durability across wet runs in the Peak District, alpine hikes, and multi-day fastpacking missions.
Key Specifications
| Feature | Details |
|---|---|
| Weight | ~100g (Men’s Medium) |
| Fabric | 2.5L Pertex Shield (7 denier) |
| Waterproof Rating | 15,000mm hydrostatic head |
| Breathability | 20,000g/m²/24hr MVTR |
| Fit | Athletic; unisex sizing |
| Features | Half zip, elastic hood, elastic hem + cuffs |
| Pack Size | Fits into palm-sized mesh pouch |
| Price (RRP) | £150 (commonly available for ~£120 online) |
Design and Construction
The Minimus Nano lives up to its name: this is about as minimal as waterproof trail jackets get.
- Pertex Shield 2.5-layer fabric uses a 7D face textile — among the thinnest yet most functional waterproof layers available.
- Half-length zip and elasticated hood cut weight, while still allowing airflow control and basic venting.
- No hand pockets, internal mesh, or excess seams — every detail stripped for gram savings.
- Taped seams throughout, including around cuffs and shoulders, ensure full waterproofing despite the lightweight build.
Available in men’s and women’s sizing, the Nano offers a streamlined silhouette that hugs closely while allowing high arm swing and torso movement.
For runners, cyclists, or fastpackers focused on grams-per-function, this jacket is engineered to disappear into your vest or pocket until weather rolls in.
Fit and Comfort
The athletic cut is designed for layering over a slim base — not bulky insulation — and excels in motion:
- Drop hem protects the lower back during forward-leaning runs
- Elastic cuffs seal comfortably without restriction
- Helmet-compatible hood adjusts automatically thanks to elastic edge binding
- Half-zip allows quick dump of heat without flapping fabric
We tested sizes medium and large across runners between 5’10” and 6’1″. The fit was close—but not clingy—allowing plenty of range without riding up. The shell’s ultralight nature gives it a barely-there feel, especially during ascents and aerobic efforts.
Waterproof Performance
With a 15,000mm hydrostatic head and full seam sealing, the Minimus Nano can handle steady rain, drizzle, and short deluges. However:
- Fabric wet-out occurs faster than 3L membranes, particularly under pack straps or sustained shoulder movement.
- DWR coating is effective, but prone to degradation over time—frequent reproofing advised.
- No storm flap over zip — internal gutter channels help, but water can enter in horizontal downpours.
The Nano shines in light to moderate rain and sudden changes in mountain conditions — exactly the use case it’s designed for. If you’re facing persistent downpours or exposed hiking over hours, a 3L shell might serve better. But for 90% of trail situations, it offers real protection with minimal penalty.
Breathability and Venting
Rated at 20,000g/m²/24hr MVTR, the Pertex Shield fabric breathes surprisingly well:
- Fast-moving trail runs at 8–10°C produced minimal condensation
- During hill reps and hard climbs, moisture escaped quickly without feeling clammy
- Half-zip allowed quick thermal dump on summit transitions or post-effort cooldowns
That said, without pit zips or full-length opening, the jacket can accumulate heat faster than vented race shells. It’s breathable enough to wear during high-output activity — just not designed for hours of continuous exertion under driving rain.
Packability and Weight
At just ~100g and sized for a mesh pouch smaller than a trail mix bar, this jacket defines ultralight:
- Packs into hydration vest, cycling jersey pocket, or dry bag side sleeve
- Fits in palm — ideal for minimalist fastpackers and race runners
- Adds negligible weight to gear lists under 5kg
Its size makes it a must-have for mountain race kits, FKT attempts, or ultramarathons with mandatory waterproof gear.
On the Trail: Use Cases and Terrain
We used the Minimus Nano on:
- Peak District bog trots under sudden spring storms
- Climbs on Snowdon and Helvellyn with gusting wind and light rain
- Trail races and tempo training in wet 8–12°C conditions
- Fastpacking loops in Scotland, as part of a just-in-case kit
In every case, it deployed quickly, held up to unexpected showers, and packed away without drama. While not a jacket for weeklong rain exposure, it’s ideal for any athlete or hillwalker needing responsive, packable protection without weight trade-offs.
Durability and Long-Term Impressions
After three months of use:
- No seam failures, delamination, or zipper issues
- Some signs of abrasion around pack strap zones — expected for a 7D textile
- Elastic hood edge remains firm and functional
- DWR performance reduced slightly — Nikwax TX.Direct restored initial repellency
Expect ~12–18 months of high-performance use before significant wear appears. Proper storage and wash cycles with waterproof garment cleaner will extend lifespan.
Comparisons: Montane Minimus Nano vs Lightweight Rivals
| Jacket | Weight | Waterproof Rating | Breathability | Best Use Case | Price |
|---|---|---|---|---|---|
| Montane Minimus Nano | ~100g | 15,000mm | 20,000 MVTR | Emergency shell, trail running | £150 |
| Patagonia Storm Racer | ~170g | 20,000mm+ | Moderate | Trail races, ultrarunning | £220 |
| Salomon Bonatti Race | ~120g | 10,000mm | High | Race compliance, summer storms | £130 |
| Arc’teryx Norvan SL Hoody | ~130g | 20,000mm | High | Minimalist alpine running | £270 |
The Nano offers the lightest and most compact profile of the group, with competitive waterproofing and breathability — making it one of the best value options for ultralight runners seeking reliability over extended features.
Pros
- Ultralight design at ~100g
- Highly packable into vest, jersey, or dry bag
- Reliable waterproof performance in variable conditions
- Breathable for trail running and active movement
- Seam-sealed with excellent fit for running dynamics
- Ideal for race-day or emergency layer situations
- Good price-to-performance value
Cons
- No full zip or pit zips
- Less durable than heavier waterproof shells
- Not suitable for sustained heavy rain exposure
- Elastic cuffs may soak and chill over time
- Requires regular DWR maintenance
Final Verdict
The Montane Minimus Nano Pull-On Jacket delivers what most trail runners and fastpackers crave: reliable waterproof performance in a package so light it disappears until needed. It doesn’t try to be a hiking jacket or alpine shell—it’s a speed-first, minimalist layer for those who chase miles in unpredictable conditions.
Its low bulk, strong breathability, and streamlined features make it a standout for mandatory race kits, mountain runs, and ultralight fastpacking. If you’re tired of hauling oversized shells “just in case,” this one earns a place in your vest.
Rating: 9.3/10
Best For: Trail runners, mountain racers, ultralight fastpackers
Avoid If: You need full-weather alpine protection or heavy abrasion resistance
