Mammut Aenergy Trail Vest 12 Review

When I think Mammut, I think alpinism. Theirs has always been the world of ice, rock, and snow; jagged peaks, and cutting edge climbing, all with a striking Euro style. Trail running has gotten more and more wild over the past decades though, and anyone familiar with Kilian Jornet can attest that at the edge of the spectrum, the lines are blurred. Mammut has put itself in that rugged trail space with natural ease, and the Aenergy Trail Vest 12 is decent proof of that.

Mammut Aenergy Trail Vest 12 Features:

• Two front stretch pockets, ideal for food storage
• Two zippered front pockets to secure items like a Smartphone
• Easily accessible stretch top pocket for items like gloves, hat or jacket
• Main compartment accessible from back opening
• One zippered shoulder pocket for keys
• Large mesh pocket for extra storage
• Multiple options for securing poles
• Recco safety feature integrated
• Four replacement cords included
• Made with durable ripstop fabric
• TriPoint Adjust: fast, adjustable and comfortable tightening system
• Wide breathable 3D mesh
• Weight: 345g (Size Medium, measured on my scale with empty softflasks)
• MSRP: $150

The New Storage King

I tend to love testing trail running vests. In general, they clarify their quality very quickly. If it doesn’t have enough storage or the storage isn’t well-designed, you know pretty quickly. If the fit or adjustment isn’t quite right, you become aware the moment you first clop down the trail. The materials are similarly up front. There just aren’t many secrets that take months to uncover.

So it is with the Aenergy Trail Vest 12. A brief inspection reveals that there are more pockets than the most obnoxious cargo shorts you’ve ever seen. The nooks, crannies, and caverns of this vest are almost too plentiful to be knowable at all. It has 15 separate compartments for storage… 15. Four of those are zippered, but all of them hold their contents securely while you’re bouncing down the trail.

And that’s the thing about the storage on this vest: while that may be a staggering number of pockets and hidey-holes, they’re all designed with thought and intention. I can’t think of a single time when I’ve used all 15 compartments at once, but I can say that they’re all up to the task and worth using. 12 liters of storage space feels like it goes a long way on the Aenergy, and that doesn’t even address the myriad ways in which it’s equipped to hold poles.

Probably my favorite pockets on the vest are on the front. The two which hold the soft flasks are good, and the two open elastic pockets below them are good as well. Both do their job and keep contents inside. It’s the zippered front pockets which I really love. They hold a large phone well, and they’re easy to get into and out of.

I have a special feeling of dread and loss when I realize that somewhere in the preceding 10 miles or so, a goo or some other such thing hopped out of my vest and found a new home on the trail. Just this past winter I had to retrace my steps to track down my phone, which I found half-submerged in a puddle of muddy water… lucky break, honestly. No matter how good a vests’ elasticated pockets are, a zippered pocket is better, and the Aenergy has two really big ones right up front. I love them.

Materials choice for all the pockets and for the body of the vest is good, I think. Everything is appropriately stretchy, but has also proven to be durable over the course of my 4+ months running with it so far. If there’s any gripe I have with materials, it’s with the mesh back. It’s not bad, per se, but I’ve run in vests which are more comfortable when it’s hot enough to run shirtless. It’s not abrasive in any way, and it’s not something I ever notice when I’m running with a shirt on, it’s just a teeny tiny bit scratchy when I’m bare against it. It is minor though.

Breathability-wise, it’s decent. I’d put it about on par with the Solomon Adv Skin 12L, not quite as breathable as the Nathan Pinnacle Pro 12L. My personal standard for breathability in a high-capacity running vest is Patagonia’s Slope Runner, but I await a dethroning, and the Aenergy isn’t quite in the realm to do it. Still, as a person who runs in the Pacific Northwest, most of my running is in 40-65 degree weather, so top-tier breathability is only a brief, seasonal requirement. The Aenergy meets my needs 95% of the time in the breathability department.

Besides, overall comfort is about more than just one thing. The Aenergy has a generally good shape and fit, and the closure system is one worthy of imitation. Mammut calls it TriPoint Adjust, and it really just comes down to two clasp points which are each secured by two anchors on the other side of the vest, forming triangles of elastic cord. They’re quick to adjust, easy to seat, and stretch naturally with the expansion of your chest as you breathe. For both security and mobility, they’re a real win.

The only thing about the fit that didn’t work well for me was the cut around the back of the neck. The vest feels just a tad too high around the nape, and I notice it as I run. It’s never been a source of chafing, or anything extreme of that nature, but I can feel it. For me, it’s a mild distraction, but nothing more. Still, worth noting.

What else is there to say? Well, it’s priced in the neighborhood a person might expect. It also has a notable variety of sizes. In my experience, they feel true to size, but the quantity of options is a bit larger than most other vests. And weight. It’s 345 grams with empty soft flasks. I wouldn’t call it heavy by any stretch, but it’s also not a cutting-edge gram-shaver. I’d call it sort of middle of the pack in that department. If I were to classify the Aenergy generally, I’d call it a hearty mountain-running pack. It’s got the storage for anything, favors burlier material over weight-savings, and wears best at or below 70 degrees. It’s ideal for the wild ridge-lines on which Mammut has always belonged.

Fit: I’m a lean 170lbs, 5’11” and typically wear a size medium or large T-shirt. I tested a size Medium vest here, and I think that sizing choice was right for me. Although the neck felt a bit high, all other proportions were right on.

Buy Now: Available at Mammut