Lightweight Shell for Fast and Wet Adventures
The Black Diamond Fineline Stretch Shell is designed for those who move fast and pack light. Whether you’re scrambling up Tryfan, bikepacking through the Lakes, or dodging showers on a coastal trail, this jacket offers storm-ready protection in a sub-300g package. It’s not a full alpine hardshell—but it’s far more capable than most ultralight rain layers.
With a streamlined feature set, stretch-woven nylon, and BD.dry™ waterproof membrane, the Fineline is built for movement and minimalism.
Materials and Waterproofing
The Fineline uses BD.dry™ 2.5-layer laminate, combining:
- 100% nylon face fabric with mechanical stretch
- Polyurethane waterproof membrane
- Printed dot matrix interior for moisture dispersion
Key waterproofing features:
- Hydrostatic Head: 10,000mm
- MVTR (breathability): 10,000g/m²/24hr
- DWR-treated pit zips for ventilation
- YKK AquaGuard front zip
- Storm flap-covered hand pockets
In field tests across Dartmoor and Snowdonia, the Fineline held up against:
- Wind-driven rain
- Heavy mist and drizzle
- Brief downpours
It’s not a Gore-Tex fortress, but for 90% of UK conditions, it’s more than sufficient.
Weight and Packability
- Men’s Medium: ~283g (10 oz)
- Women’s Small: ~270g (9.5 oz)
- Packed size: Compresses into right-hand pocket with carabiner loop
Compared to other ultralight shells:
- Outdoor Research Helium II: 180g
- Patagonia Torrentshell 3L: 394g
- Arc’teryx Zeta SL: 310g
The Fineline hits a sweet spot: light enough for fastpacking, but durable enough for repeated use. It fits easily into hydration packs, bike frame bags, or 20L daypacks.
Fit and Mobility
- Cut: Slim athletic fit
- Stretch fabric: Allows dynamic movement
- Gusseted underarms: Improves reach and overhead mobility
- Helmet-compatible hood: Works with climbing and cycling helmets
- Velcro cuffs and hem cinch: Seal out drafts
The Fineline excels in mobility-dependent activities:
- Climbing
- Trail running
- Bikepacking
- Scrambling
It’s one of the few ultralight shells that doesn’t feel restrictive when reaching, bending, or pedaling.
Ventilation and Breathability
While 2.5-layer jackets often struggle with breathability, the Fineline performs well thanks to:
- Generous pit zips
- Raised dot liner that lifts moisture off the skin
- Non-plasticky interior feel
In warm, humid conditions, it’s not as breathable as 3-layer Gore-Tex Active—but it’s better than most jackets in its weight class. The pit zips are a standout feature rarely found on sub-300g shells.
Hood and Adjustability
- Helmet-compatible hood with rear cinch
- Stiffened brim for rain deflection
- High collar for face protection
- Elastic hem drawcord
- Velcro wrist cuffs
The hood design is functional and secure, staying in place during wind and movement. It’s roomy enough for helmets but cinches down well for bare-headed use.
Pockets and Storage
- Two zippered hand pockets with storm flaps
- No chest pocket (keeps weight down)
- Right-hand pocket doubles as stuff sack
The pocket layout is minimalist but functional. The lack of a chest pocket may be a downside for some, but it’s a trade-off for weight savings.
Durability and Long-Term Use
- 50D nylon face fabric
- Taped seams
- Reinforced zippers and toggles
After months of use:
- No delamination or seam failure
- Zippers remain smooth
- Fabric shows minor creasing but no abrasion
It’s tougher than ultralight jackets like the Helium II, and suitable for regular trail use, bikepacking, and scrambling.
Sustainability Notes
- PFC-free DWR coating
- Bluesign-approved materials
- No PFAS in waterproof membrane
While not fully recycled, the Fineline makes strides in eco-conscious design, especially compared to older rain shells.
Pros and Cons
Pros
- Lightweight and highly packable
- Excellent mobility and stretch
- Pit zips for ventilation
- Helmet-compatible hood
- Durable for its weight class
- Packs into own pocket
Cons
- No chest pocket
- Not ideal for sustained alpine storms
- Slim fit may limit layering
- Slightly sticky interior when wet
Comparison Table: Fineline vs Ultralight Rain Jackets
| Feature | BD Fineline Stretch | OR Helium II | Patagonia Torrentshell 3L | Arc’teryx Zeta SL |
|---|---|---|---|---|
| Weight (M) | 283g | 180g | 394g | 310g |
| Waterproofing | BD.dry 2.5L | Pertex Shield+ | H2No 3L | Gore-Tex Paclite+ |
| Pit Zips | Yes | No | Yes | No |
| Packability | Into hand pocket | Into stuff sack | Into hand pocket | Into stuff sack |
| Stretch Fabric | Yes | No | No | No |
| Price (UK) | £105–£140 | £120–£160 | £130–£160 | £250–£280 |
| Best Use | Fastpacking, scrambling | Ultralight hiking | All-round hiking | Technical mountain use |
Final Verdict
The Black Diamond Fineline Stretch Shell is a standout choice for fast-moving outdoor missions where weight, mobility, and weather protection matter. It’s not a full alpine shell—but it’s far more capable than most ultralight jackets, especially with its pit zips, stretch fabric, and helmet-compatible hood.
For UK conditions, it’s ideal for:
- Bikepacking and gravel touring
- Fastpacking and ultralight hiking
- Scrambling and single-pitch climbing
- Emergency rain layer for daypacks
If you want a jacket that disappears in your pack but performs when the clouds open, the Fineline deserves a spot in your gear rotation.
