La Sportiva's striking new Aequilibrium range of mountain boots aim to balance comfort, technical performance and durability against overall lightness. The Aequilibrium series is aimed at light-and fast alpine days, mountain trekking, glacier crossings and via ferrata on mixed terrain - but we'd say they work equally well on a classic Scottish ridge.
The range includes three models:
- Aequilibrium Top GTX, the boot most suited to alpine mountaineering, with an integrated gaiter - £435
- Aequilibrium LT GTX, a part leather upper boot designed for high level backpacking with heavy loads - £325
- Aequilibrium ST GTX, the lightest in the series, well suited to less technical mountaineering and hillwalking - £295
I have found the synthetic upper version (Aequilibrium ST GTX) a fantastic boot in the Scottish mountains throughout winter and early spring, on days when technical winter climbing is not on the agenda. Though they take the heel of a semi step-in crampon, in conventional boot terms I'd rate them as B1.
On the home scales I make these boots to be 1435g / pair in size EU44 (La Sportiva quote 1260g / pair Size EU42). They certainly are light, and roughly comparable in weight to Scarpa's Ribelle Lite, to take one obvious near competitor. Although there are some other modern mountain boots out there that are lighter, the Aequilibrium's use of lightweight design and materials gives you some added performance for those longer demanding days where you want to reduce the fatigue.
The Aequilibrium series is available in both men's and lower volume women's fit (although the built-in-gaitered version, Aequilibrium Top, is not offered in the female fit). Overall width and volume seems about middle of the road. For context I take a EU44/UK9.5 street shoe and my feet are reasonably standard, if only slightly on the narrow side. I decided to try EU44 in the Aequilibrium, which felt perfect with a thick sock on. To my surprise, I was able to wear these right out of the box without any problems for a day in the Southern Highlands. This may not be the case for everyone so best to try on before purchasing and ensure the fit is right.
The sole of the Aequilibrium is arguably the most innovative part of the boot
With this in mind, the sole of these boots doesn't appear to be either notably narrow or wide, and my pair feels perfect in length to allow for space for the toe when on long downhills. The toe box fits me perfectly across the width and allows for some vertical wiggle room to keep circulation going without any excess dead space.
My heel is been held solidly by a comfortable amount of padding to avoid any heel lift, but the fit here is not so tight that there is unwanted pressure placed on my achilles, a problem that I suffered from with my previous boots.
Along the top of my foot feels comfortable with an even distribution of pressure achieved with the lacing system. If I was to be harsh there can be a slightly cramped feeling caused by the tongue around the shin which I can sometimes feel towards the end of a day. I have thin legs so that's maybe something for others to consider, but far from a deal-breaker for me.
At the collar my ankle has the ability to flex well due to its lower than average cut and soft build. The back of the collar is an elasticated region that helps to easily get the boots on and wraps closely to the leg to avoid snow or grit getting in. This allows for freedom of movement which is great for an uninhibited full day of walking, but thanks to the softness here the boot does provide less support on steep snow or when front pointing.
The Aequilibriums use a Gore-Tex Performance Comfort lining to achieve a breathable waterproofing which has kept my feet dry in the snow and prolonged wet - there was some wetting through at the heel after a day of extensive boggy terrain, but this did seem inevitable and light occasional bog hasn't been a problem. The insulation is moderate throughout most of the boot which is perfect for days where I have been staying active in the cold, and just stopping briefly for lunch. These aren't the best boots for hanging about at a winter belay but that's not where these are designed to be used.
The previously mentioned elasticated "heel gaiter" (although this is not really a gaiter) is showing some small signs of wear where my achilles has been rubbing against the soft material. There is also little in the way of insulation in this region although this thinness does benefit freedom of movement. This flexibility at the ankle is also assisted with the contoured 3D Flex ankle system (used in other La Sportiva boots) which allows for a fair range of movement in the ankle, and this has felt great on long days where I want an unrestrictive and light-feeling boot.
The tongue is sewn into the upper of the boot from the very top and extends down to cover the laces in the toe region to protect against wear. However, it appears as though the laces are sewn into the boot here which would appear to make changing them quite difficult without compromising the tongue material - something which could bother some.
La Sportiva's 'HoneyComb Guard' material is a lightweight, durable, and abrasion-resistant nylon (nylon 6.6) which is used strategically on main sections of the upper around the top of the foot and collar. This hasn't shown any notable signs of wear so far and feels suitably tough. The lower section of the upper is reinforced with a lightweight thermoplastic polyurethane (TPU) which has a high abrasion and wear resistance and has done the job of protecting against scuffs and grime in this exposed area.
The heel and toe-cap are also made from a more robust feeling TPU which provides the boot with a lot of rigidity, as well as looking pretty flash. These sections feel really durable and have provided my heels and toes with a lot of protection from bumps. The heel area also has a ledge to accommodate a semi-automatic C2 crampon. However, I consider these boots to be more like a B1 boot that can take a C2 crampon tan a full B2 (see the section on sole construction below).
The sole of the Aequilibrium is arguably the most innovative part of the boot. It's certainly the most striking, particularly in the heel where there are effectively two aggressive heel areas. I've found these perform well, biting in and assisting with braking on the downhill across a variety of terrain. Whilst out with a friend descending on wet grass, I could literally run downhill while he repeatedly fell.
Right at the back, the heel sharply cuts up, much more than your average cutaway heel, which has helped provide a more natural rolling stride along with the natural rocker at the front of the sole. Whilst this is great for reducing fatigue whilst walking - and a good reason to consider these boots - it's worth checking if this design will be compatible with the crampons you intend to use. The double heel at the back hasn't quite married perfectly with my Petzl Lynx crampons, which has been fine for general walking and mountaineering but would stop me from taking them on any more technical terrain.
The Aequilibrium is the first product to use Vibram's catchily-titled SpringLug Tech tread ,which is designed to prioritise comfort and adaptability to the ground whilst keeping the boot light. The construction consists of the rubber outsole and a low-density polyurethane injected within which has allowed La Sportiva to do away with a midsole.
This outsole construction definitely feels ever so slightly softer and more giving when pressed with the fingers when compared side by side with my partner's La Sportiva Trango Towers and Scarpa Ribelle Lites. This slight 'give' in the sole of the Aequilibriums probably does contribute to the comfortable and cushioned walking experience, and the lightweight PU means less a lighter boot overall, and thus less fatigue throughout the day. This slightly softer construction will no doubt lead to faster wear in the sole in comparison to some of the competition. However, the sole and lugs on the Aequilibrium are so beefy that it doesn't concern me so much and I have yet to see any significant wear. Since this midsole is relatively flexible, these boots have felt fine on moderately technical terrain, but wouldn't be a great choice for anything approaching serious winter climbing.
The Aequilibrium ST is a remarkably comfortable and lightweight boot that's been in its element on steep winter snow slopes, mountaineering ridges, and rough walking/scrambling terrain in Scotland. Despite a few minor niggles, these boots will now be my go-to for covering long distances in the Scottish winter hills, or for a summer rock trip to the Alps when fast and light is prioritised and clunkier and more technical winter boots would be overkill. In terms of modern design and technology, these funky boots feel like a step up.
La Sportiva say:
Aequilibrium ST GTX is the lightweight, technical boot ideal for via ferrata, trekking and crossings in glaciers and on mixed terrain. Maximum comfort is guaranteed thanks to the tongue with the soft snow guard on the collar. Exceptional walkability thanks to the innovative construction of the Double Heel™ heel: the very pronounced double-wedge rear geometry increases the braking effect downhill and allows a smoother rolling, reducing muscle fatigue.
Durability and lightweight coexist in harmony thanks to the new outsole / midsole package with external Rubber Guard™ shell construction and internal foam material for accentuated cushioning and enhanced lightweight derived from less use of rubber layers. The shape is Ergonomic: enveloping and precise with TPU shells integrated in the toe and heel to reinforce the upper. The 3D Flex System Evo™ directional joint with shaped malleolus and abrasion resistant protection, allows better control of the support and perfect mobility of the ankle. The toe protection at the toe lacing protects against chafing. The midsole is semi-cramponable, the sole adopts a Vibram® SpringLug Tech tread with Impact Brake System lugs for greater adaptability to hard rock surfaces.
- Sizes: 36-48 (men) 36-42 (women)
- Weight: 1435g / pair in size 44 (our weight)
- Uppers: Water-repellent high-tenacity Nylon 60.6 with abrasion resistant zones Honey Comb Guard
- Lining: Gore-Tex Performance Comfort
- Insole: Carbon loaded nylon
- Midsole: None
- Sole: Vibram® SpringLug Tech rubber and PU foam inner lining