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K2 Ski Boots

About our boot commentaries

If you’re a close observer of the ski equipment market, you might be excused for thinking said market was well served in the alpine boot department. If you were selling boots in the mid-1970’s, you also had the chance to experience K2’s last effort to re-imagine alpine footwear.  As to the merits of this ancient attempt, let’s just say it didn’t kowtow to conventional notions of fit or performance.

This time around, K2 has done its homework and produced a far more conventional product. As America’s preeminent ski brand, K2 has made the core recreational skier—and not the race competitor—the focus of their best engineering. This philosophy has been extended to the new boot line, where K2 has aimed at the all-terrain, big mountain skier as the top-end target. To take an obvious example of how this orientation finds expression in the new shoes, flip one over. The sole of a race boot tends to be single, monoblock structure, but the Spyne series uses a grippy sole that’s a far better solution if you’re climbing a rocky ridge or riding a snowmobile in the backcountry.

The central feature from which the Spyne derives its name is the Powerfuse Spyne, a carbon exoskeleton that adds rigidity in the rear, allowing the rest of the boot structure to be a more effective shock absorber. This is a design element that, in conjunction with the Energy Interlock that controls the rivet-less rear connection between shell and cuff, makes the K2’s particularly well suited to charging through the irregular terrain features and broken snow conditions that prevail off piste.

In another echo of their ski origins, for every Spyne there is a Spyre, or a parallel female-specific boot made for the go-everywhere gal. Both Spyne and Spyre flagship models use a Precisionfit Intuition liner that takes full advantage of this heat-moldable, custom inner-boot technology.

In the two years since K2 debuted boots, they’ve had to compete against a Salomon boot that has that has taken a chunk out of everyone’s butt, yet they’ve used clout earned as the preeminent ski brand of the last decade, as well as innovative boot-technicity, to grab and hold a piece of the specialty retail pie.

K2 deserves special commendation for introducing their boot into a brutally competitive market and never wavering on the first principle of their commercial plan: they would not, have not and will not authorize the sale of their boots on the Internet. K2 is run by skiers. They understand the special requirements entailed in fitting a boot properly, an exercise that can only be accomplished long distance with the intervention of a thousand angels. Since most angels are busy elsewhere, we wouldn’t count on them sorting out boot-buying on the Internet anytime soon.

abbThis button takes you to the relevant America's Best Bootfitters review.

gender flex differences



narrow (LV)
medium  wide (HV)
Flexes: 130, 110, 90*

*HV only


K2 deserves a lot of credit for resisting the temptation to re-invent the alpine ski boot.  Not that they didn’t do their due diligence and re-think the requirements, but their thinking led them back to a fresh take on some well-established concepts.  The Spyne 130, whether in its high-volume (HV), low-volume (LV) or relatively roomy medium issue, works because it meets every expectation for performance, and then adds a little extra feature/benefit that assists the all-terrain skier.

Yes, the stance is spot on, but the rigid spine (its signature feature) coupled to a well-conforming cuff keeps the skier in a centered stance that is also elastic.  The Intuition® inner boot does as much with the heat-moldable concept as any stock liner extant, although it feels skiable right out to the box.  The flagship Spyne 130 doesn’t have any more built-in features than other boots, but every component from the sole to the power strap has a smoothly integrated extra touch.

The same fit options that grace the Spyne 130 are also on display in the slightly softer Spyne 110. The Spyne 110 feels a little more substantial than most 110-flex boots, which makes it a strong candidate for any expert skier who motors through chunder on a relatively short, rockered ski.  While the LuxFit Intuition® liner on the 110 can be heat molded, it feels ready to ski from the moment it’s buckled up.

The Spyne 90 is only available in the wide HV last and the more relaxed CushFit Intuition® liner, so it’s not a precision machine like its beefier brothers.  
But it’s not mushy flexing and the ankle fit remains snug despite the wide forefoot dimension.  Along with its uncompromised stance and firmer-than-the-field flex, the snugger ankle area improves the Spyne 90’s steering control in all conditions.  It’s a good choice and a good value for the skier still developing their all-terrain skills.


♀ Spyre

narrow (LV)
medium  wide (HV)
Flexes: 110W*, 100W**, 80W***

*No HV, **No LV, ***HV only


K2’s line of ladies’ boots parallels the men’s collection in most respects, but instead of offering a full range of widths the women’s collection has only one or two lasts per model. The stout Spyre 110 offers a choice of narrow or medium; the Spyre 100 comes in medium or wide; and the soft 80 is available only in wide.  All get a shorter cuff and a women-specific, narrow heel pocket built into a moldable Intuition® liner.  

Otherwise the new K2 women’s models deploy the same well-conceived technology found in the men’s line.

The sweetspot for value, price and performance – in addition to fit and function – resides in the Spyre 100.  The boot retains the PowerFuse Spyne and Energy Interlock system that give the K2’s their personality, and a heat-moldable, LuxFit  Intuition® inner boot is standard issue.

One could make the case that if a boot holds you comfortably in the correct stance, it’s done its job.   The wide-lasted Spyre 80 sticks to the basics, putting the intermediate woman in a position to advance.  What it lacks in frills it makes up for in fundamentals.



narrow (LV)
medium  wide (HV)
Flexes: 130*, 110**,100***
hike mode

*No HV, **No LV, ***HV only


K2 had an advantage when they built their first hike-mode (HM) boot: they hadn’t made any boots, so they could build the HM model from the ground up.  Since making a killer BC boot was central to their line from the outset, they built an alpine boot technology, Energy InterlockTM, which was easily adaptable to hiking.  This is why Synchro InterlockTM, K2’s HM mechanism, has first-in-class rear support without losing the needed range of motion to make hiking feasible.
K2 also concocted a replaceable walking sole that will work with any binding from everyday alpine to high-tech Dynafit, and they offer it all with a narrow (97mm) or medium (100mm) PrecisionFit Tour Intuition® liner in the top-of-series 130.    The Pinnacle 110 comes in either medium (100mm) or wide (102), and the Pinnacle 100 gives big feet a chance to live the sidecountry lifestyle with a wide-ass 102 last.


♀ Minaret

medium / wide (HV)
Flexes: 100W*,  80W***
hike mode

*No HV,  ***HV only


K2 isn’t confused about who’s likely to end up in either of the new Minarets, the women’s incarnations of the men’s Pinnacle HM boots.  The stiffer 100 uses a medium-volume 100mm last in an accurate LuxFit Tour liner, so when this woman says she’s hiking to the top, she’s not kidding.  The Minaret 80 lady isn’t likely to hike further than necessary, but when she does have to hoof it, she at least doesn’t want to walk like a zombie.

About Our Boot Commentaries

Please note that we don’t use the term reviews. We want to distinguish between our ski reviews— which draw directly from on-snow experience—and our boot coverage, which does not. Our confreres Steve Cohen and Mark Elling of Masterfit Enterprises convene an expert panel of judges to test boots, so we leave most references to on-hill comportment to Cohen & Elling's America's Best Bootfitters reviews.

Please note as well that our comments cover not individual boots, but families of boots within each brand's collection, even though we often depict the top member of that family. This is why a single report can indicate multiple flexes and widths.

It has become industry cant to define a boot’s overall fit volume by its forefoot width, given in millimeters. Boots that are “98’s” are narrow, while “104’s” are bathtubs. The problem with these numbers is they tend to be, well, wrong. What’s true, however, is that a boot calling itself a “98” will be lower volume (in the same size) than a boot calling itself a “100.”

For accuracy, we’re substituting Narrow, Medium and Wide for numeric designations that only occasionally intersect with reality.

hike mode This symbol indicates a boot with hike mode

A shorter cuff (which affects flex) is the defining trait of all women’s boots, so a women’s 90 most often isn’t going to be the same flex as the men’s 90.

Respecting this inherent difference, we append a “W” to all women’s boots’ flex numbers.