The North Face Summit Series L5 Shell Pants

Summit Series L5 Shell Pants

Size Tested: Medium

Stated Weight: 400 g

Stated Features:

• Engineered fabric and articulated patterning designed specifically for alpine comfort and mobility
  Fully featured pants are waterproof, seam-sealed and crafted of our most breathable DryVent 3L fabric to date
• Nylon fabric with localized FuseForm construction for durability where needed most with minimal seams
• One-piece construction with localized durability in high wear areas allows for less seam tape and delivers comfort, breathability and performance with less weight
• Crotch gusset for added mobility in alpine environments
• Integrated belt for personalized fit
• 2-way center front zip for optimal harness compatibility
• Side zip venting
• Pack/harness friendly pockets
• Zip ankle closure for easy access to boots

MSRP: $450 USD

Reviewer: 5’10”, 135 lbs

Days Tested: 6

Test Locations: Aspen, CO; Vaud and Berner Oberland Switzerland

The L5 pants are part of The North Face’s new Summit Series — historically it’s been an alpine-focused yet consumer-accessible part of the TNF line. But this year, The North Face has flipped the script a bit on the Summit Series.

The new Summit Series is clearly an experimental line, and available in limited quantities. The line consists of only 7 pieces: a shell jacket and pant, three insulators, and two baselayers / thin insulators. It’s essentially a full alpine kit—everything you need to be at altitude in the mountains.

The new Summit Series is a parade of all the best and most cutting edge of TNF’s in-house developments. And from what I’ve seen, those are pretty damn awesome. I’ll be reviewing both the L5 pant and the L4 insulator, and overall, I’m very impressed with the Summit Series. We’ll start off here with the L5 pant.

 

First Impressions

I have seen (and made) a lot of outerwear in my fairly short life. From cutting-edge Arc’teryx products to $7k Bogner high fashion pieces to $24 Costco softshells, I’ve seen just about everything out there. So let that provide some context for this next statement: the L5 pants are the most beautiful piece of outerwear I have ever seen.

Putting personal style preference aside for a moment to focus specifically on (1) outerwear construction, (2) attention to detail and (3) the merger of form and function, the L5 is the most perfectly constructed and thought out piece of outerwear I’ve seen, ever.

There are two things that make the L5 pant gorgeous.

(1) TNF’s new FuseForm fabric milling technology. (Specifically, how it is used in the L5. More on that below.)

(2) Their simple design with a classic silhouette.

Let’s now talk a bit about this new FuseForm technology that TNF is using.

FuseForm Technology

The principle behind FuseForm is not all that new, in fact it has been going on for centuries. FuseForm mixes different fibers together in the milling process—the same way that heathered fabrics are made.

What sets FuseForm apart is the level of control that The North Face has over where each of these fibers is incorporated into the weave. TNF designers use FuseForm to blend fibers of different weights (denier) into finished fabrics, changing the ratio of high denier to low denier over specific sections of the fabric. This denier gradient fabric is then cut so that the high denier part of the fabric is sewn into the high wear areas of a garment (shoulders, knees, elbows etc…).

Traditionally, companies would mill two completely separate fabrics, one low denier and one high denier, then patch together a garment with the two fabrics to achieve the same effect. The problem with this technique is that it creates a huge number of seams. And more seams = less breathability, less durability, more weight and more labor to make.

With FuseForm, TNF creates a similar effect without the additional seams. And this is just the first year TNF is using this technology. Who knows what kind of wild applications TNF will find for FuseForm in the future.

To me, this feels like a paradigm-changing technology, similar to what 3L construction was 15 years ago.

Milling fabrics is one of the historically inflexible pieces of the outerwear supply chain. You estimate your yardage need, dial in the colors, and define your weave. A few months later, you get a few rolls of fabric from some giant fabric mill. The larger your order the more control you have, and vice versa.

With FuseForm technology, the milling must be a completely different endeavor. Specific patterns of denier ratio must be defined and then repeated periodically throughout the length of the fabric. The exact number of final pieces and size distributions must be defined ahead of time. Once that is settled, you press a button and wait.

Fabric cutting must be 100% defined by the milling process. Cutting guides are likely milled into the fabric to ensure cutting accuracy. Each piece must be 100% finalized before any fabric is milled — which is not how things are currently done.

To be clear, most of the above is speculation; I don’t know the specifics of the TNF process, but I think it is safe to say that this technology is a huge departure from standard outerwear production techniques. So this could change the whole industry, or it could be too complex and peter out. My gut feeling is that the initial complexities of changing the way the production process runs will quickly yield to better efficiency, and in fact, simpler production. We’ll have to wait and see.

Why is the new Summit Series a limited production run? My guess is that The North Face is working on streamlining this new production process before it is rolled out in huge quantities. Anyway, back to the L5 pant…

Construction

TNF uses the FuseForm tech a bit differently on this pant. In their more commercial line of FuseForm pieces, the denier gradient is slow and takes place over the space of several inches, slowly transitioning from light to heavier fibers.

In the L5 pant, the two different denier fibers are two different colors (black = low denier and gray = high denier). As you can see by looking at the pant, the denier transition is not smooth or gradual at all, it is abrupt and crisp. Each “patch” is not a patch at all, rather a change in fabric weave. Without FuseForm, this pant would have about 15 seams. The L5 has 5 seams (not counting the tiny knee articulations).

This brings up the questions, is this actually useful? Will the average consumer care or even notice this new technology? How bad is a seam really?

In short, yes it’s useful, but the average consumer won’t notice and seams are livable. We’ll get into that more in the rest of the review below.

NEXT: Fit, Fabric, Etc.