Sage to Summit: Mountain Running and Fastpacking: Gear review: Salomon Advanced Skin S-Lab 5 Set

A confession: I have been wearing a children's hydration backpack--just one--on long runs for at least the last 12 years.

Children's packs aren't made to last that long. I've repaired mine with new zippers, velcro, patches, and--when the fabric became too thin to patch--surgical dressing.

No, I'm not a Luddite. Yes, I've tried other packs. But every new hydration pack I've tried has either been too long for my short torso or was made for a little person who doesn't worry how far away the next water source is or how much weight superhero decals and shiny metal stars will add to the load.

Recently, however, an inspired person at Salomon saw my complaints, left an extra-small/small "Advanced Skin S-Lab 5 Set" hydration vest within my reach, and backed quietly away.

When I saw the "XS/S" label, I didn't break into song or anything. I filled the vest, put it on, and went for a run with a careful skepticism born of too many kidney bruises. "Hmm," I said. Then I took the pack home.

The next day, I reached for my old hydration pack, hesitated, and picked up the Salomon vest instead. I may have skipped once or twice when I put the vest on and began running. I don't recall.

Comfort, fit, and mechanics:

Two words: No bounce. The Advanced Skin 5 did not bounce vertically. It did not swing horizontally. It did not chafe my shoulders or slap my back like a drunken stranger or rub raw spots on my spinal column. The vest includes load adjusters at the top of each shoulder that pull the pack in for lighter loads, so there's no sagging at the back of the pack or front-to-back bounce.

Fit-wise, Salomon has elevated the standard for chest straps and comfort. Two slim, adjustable elastic ribbons--too comfortable to honestly call chest straps--clip at three points apiece in a variety of directions to thin, slightly flexible plastic cylinders that run along the insides of the front vest panels. Taking the pack off only requires unclipping in two places--a matter of seconds. "Skin" isn't an idle boast--this hydration vest fits like...well, thankfully not exactly like a second skin, but more like a soft, comfortable T-shirt.

The "5" in "Advanced Skin S-Lab 5 Set" stands for the vest's approximately 5-liter carrying capacity, not the hydration bladder's water capacity (which is 1.5 L or slightly more than 50 ounces). Svelte though it looks, the vest hides nine pockets fore and aft in addition to the pack's main compartment (where the hydration sleeve also stashes). The front and sides include: two adjustable water bottle pockets that can be used to stow other items such as a light water treatment kit or a small camera; a smaller removable zippered pouch with room for salt and gels; a tiny detachable plastic whistle; two small mesh pockets that open at the top; and two small zippered side pockets with room for a light hat and gloves. On the back of the vest, a large zippered pocket stretches enough to hold a light jacket. Another larger pocket inside the main compartment includes two thoughtful extras from Salomon--an emergency blanket and a spare zippered pouch with velcro, which means that when you've emptied the first pouch you can simply remove it from the front and switch it out with the second pouch without having to repack everything. Other thoughtful details abound: The main compartment shuts--and stays shut--without a zipper (see "Hydration system" below). Likewise, the pouch just inside the main compartment eschews a time-consuming zipper in favor of two tiny, super-light magnets. It's easy to adjust the pack's fit and to pull things in and out of front pockets while running, even if you've got cold or swollen hands. The vest also includes Salomon's super-light "4D" leash-and-loop system for carrying poles.

Although the Advanced Skin 5 is designed for trail races and is a fine pack for a supported ultramarathon trail race, the pack's pockets also add up to sufficient space for surprisingly comfortable self-supported, shorter ultramarathon-distance (50 km or so) trail runs, assuming good weather and resupply sources for water. (For self-supported runs in variable weather or extending past sunset and snowline, it's wiser to take a larger pack for spare warm clothes and equipment.)

Thermal regulation

There's always a price for wearing a well-fitting vest over your regular running clothing: less evaporative surface area. Although this hydration vest is composed mostly of light, comfortable mesh (it weighs only 12 ounces without water; less if you remove a pocket or insulation), it's still harder to stay cool in the vest than it is to stay cool, for example, in a small backpack with no front panels, or in no hydration pack at all. The Advanced Skin 5 was pretty warm on days ranging between 60 and 65 degrees in full sunlight, particularly because I live on the sunny side of the Sierra Nevada mountains and the model I tried was black. On the other hand, I didn't notice that I was carrying water, food, and a jacket on my back--the fully loaded pack felt like a light vest. The trade in evaporation versus comfort feels worthwhile on most days, especially at the end of the day, when an ordinary backpack can wear holes in both patience and skin.

The hydration bladder stows in a reflective white sleeve with an insulated panel on the side that rests against the back. Another white panel in the main compartment protects other things stowed in the center of the vest. Anything stowed in the two rearmost pockets, however, bakes--the mesh in the black model is both translucent and dark enough to absorb plenty of heat. Careful packing reduces this problem (e.g., light jackets or other clothes packed in the rearmost pocket insulate heat-sensitive food packed in the center).

The hydration tube comes with its own removable black insulation sleeve, a feature I'm looking forward to testing out in winter conditions, when exposed hydration hoses freeze.

Hydration system

The vest comes with a BPA-, PVC- and phthalate-free 1.5 liter/50 ounce hydration bladder and Salomon's signature quick-release hose, a boon to those of us who hate to rethread hydration tubes every time we refill water. Once the hose is detached via an easily accessed port in the bottom of the pack, the bladder and sleeve pull quickly out of the top of the pack (no zippers!). A plastic clip with a leash slides from the folded top of the bladder for quick refills or cleaning. Both the bladder and hose come with insulating sleeves (see "Thermal regulation" above).

The hydration tube runs under the arm (default position) or can be rerouted over the shoulder.

The bite valve lock doesn't operate easily one-handed, nor is it obvious at a glance when flow is "on" versus "off." Since the mouthpiece doesn't squirt unless it's squeezed, it's simpler to leave the bite valve unlocked while running.

A pack that comes in three sizes is a fine thing. A pack that bounces with you instead of against you is even better. After a day of use, the Advanced Skin 5 became my default hydration pack for trail runs 50 km or shorter, even for trips short enough that I could leave hydration at home. If the folks at Salomon decide to sell the larger-capacity pack in this series (Advanced Skin S-Lab 12 Set) in a lighter, more sun-reflective color, I'll probably shut my eyes against the heady price and collect the whole Set. In the long run (ahem), it seems a small price to pay for thousands of miles of comfort.