Hello and welcome to my K2 Thraxis review.
In this review I will take a look at the Thraxis as freeride snowboard boots.
As per tradition here at SnowboardingProfiles.com I will give the Thraxis a score out of 100 (based on several factors) and see how they compare with other freeride boots.
Overall Rating
Boots: K2 Thraxis
Price: $499 (USD recommended retail)
Style: Freeride
Flex Rating: Stiff (10/10)
Flex Feel: Stiff (9.5/10)
Rating Score: 88.3/100
Compared to other Freeride Boots
Of the 14 current model freeride snowboard boots that we tested:
❄️ The Thraxis ranked 6th out of 14
Overview of the Thraxis’ Specs
Check out the tables for the Thraxis' specs.
Specs
STYLE:
FREERIDE
PRICE:
$499 - BUYING OPTIONS
Ability Level:
flex:
weight:
Felt normal
LACING SYSTEM:
Triple Boa
Sizes
US MEN'S SIZE | UK SIZE | EURO SIZE | MONDOPOINT |
|---|---|---|---|
4 | 3 | ? | 22 |
4.5 | 3.5 | ? | 22.5 |
5 | 4 | 36.5 | 23 |
5.5 | 4.5 | 37 | 23.5 |
6 | 5 | 38 | 24 |
6.5 | 5.5 | 39 | 24.5 |
7 | 6 | 39.5 | 25 |
7.5 | 6.5 | 40 | 25.5 |
8 | 7 | 40.5 | 26 |
8.5 | 7.5 | 41.5 | 26.5 |
9 | 8 | 42 | 27 |
9.5 | 8.5 | 42.5 | 27.5 |
10 | 9 | 43.5 | 28 |
10.5 | 9.5 | 44 | 28.5 |
11 | 10 | 44.5 | 29 |
11.5 | 10.5 | 45 | 29.5 |
12 | 11 | 46 | 30 |
13 | 12 | 48 | 31 |
Who are the Thraxis Most Suited to?
The Thraxis are best suited to those who like to charge hard and carve deep. They are at their best with speed beneath them and aren't at home with slow speeds.
Definitely not for beginner riders - way too stiff for that and beginners would likely find them too unforgiving.
Best matched with boards in the 7/10 to 10/10 flex range - and most ideal with boards in the 8/10 to 9/10 flex range.
The Thraxis in More Detail
O.k. let’s take a more detailed look at what the Thraxis are capable of.
Demo Info
Boots: K2 Thraxis 2025
Size: 10 (US Men's Sizing)
Date: January 15, 2025
Foot to Boot Fit
Length Fit:
My toes weren't quite touching the ends, but they were close. I feel I could've fit in a slightly shorter boot, but maybe not a full half size down. Maybe a 1/4 size down.
There was no pressure on the tops of my toes and there was a reasonable amount of wiggle room.
Width:
There was a bit of space for the sides of the toes - they weren't being pushed against the sides. Around my forefoot, there was no space on the sides, but there was also no pressure there. A good fit width-wise. I would consider them a medium width.
Top of Foot (Instep):
Initially there wasn't any pressure on my in-step, but then I felt the need to crank the BOA harness that wraps around the ankle of the liner, to get better heel hold, and then there was some pressure on the top of the foot. That pressure was not quite as far back as where instep meets ankle but close to there. It wasn't terrible by any means though. A little uncomfortable but nothing major.
Around Ankles:
When I was wearing them during our in-house testing process, I noticed a bit of a hotspot on the back of the right ankle bone, just on the underside of it a little bit. And then another hotspot on the bottom of inner ankle bone. I noted that the Thraxis felt like they rock in towards the inner part of the boot quite drastically. A lot of boots do this, but it was more pronounced in the Thraxis.
While riding in them, this ankle pressure intensified. It still existed on both the inner and outer park of the ankle bone, but it was now more pronounced on the inner ankle bone. I wonder if it was something to do with how much they rock inwards. While this wasn't bad when I first started riding in them, it got progressively worse the longer I was in them and was quite uncomfortable by the end.
True to Size?:
I’d say true to size. I feel like a 9.5 would be too small, but I could probably do a 9.75, if quarter sizes existed.
Boot to Binding Fit
Heel width: Good amount of room in there. Similar to my control boots. Maybe just a touch less space.
Toe width: Also good amount of space. Again, very similar to control boots.
Ankle Strap: Fit pretty good as it was, but fit better with the ankle strap lengthened by one hole.
Toe Strap: Again, fit ok where it was, but fit better with it lengthened by one hole.
Flex
I found these boots really stiff. Not the stiffest I've ever ridden in, but getting close to that.
Carving and Slow Speed Response
As expected from the flex, the Thraxis offered a lot more support for high speed carves and felt at their best when doing high speed carves.
They weren't much fun at slower speeds though. Where at high speeds they felt responsive and supportive, at slow speeds that translated to feeling sluggish and heavy.
Heel Hold
The heel hold was really decent. To get it how I like it, I did have to crank down the boa that tightens the internal ankle harness quite a bit, and that did lead to some in-step discomfort. But the instep discomfort was nothing major and worth it for the extra heel hold.
Adjustability
These boots are highly adjustable. They feature a triple BOA system with the front BOA tightening just the top half of the shell of the boot (completely independently of the bottom part of the shell).
Then the BOA on the inside of the boot controls the lower portion of the shell, independently of the upper portion.
The BOA on the outside side of the boot controls the harness that wraps around the ankle area of the liner of the boot. This not only allows you to adjust for better heel hold, it also means you can retighten this on the fly, without having to open up the shell first.
The liner itself doesn't actually have a lacing harness, but it does have a triple velcro strap at the top of the liner to get it more snug against the shins (more on that in the ease of entry/exit section below).
Comfort
When testing these in-house, I thought they would feel pretty comfortable on snow and the last time I tested these boots on snow, they did, so I had no reason to think otherwise. There was a little bit of in-step pressure and to a lesser extent ankle pressure, but it wasn't anything too bad.
However, my on-snow experience would be different this time. While the in-step pressure was barely noticeable after a while, the ankle pressure became progressive worse and worse and I experienced cramping.
By the end of riding in them, I was dying to take them off. I'm not sure if it was because of how much they rotate inwards (see fit section above) but whatever it was, they weren't as comfortable as my previous experience or how the in-house testing suggested they would be.
Shock Absorption
I felt they did a decent job of absorbing shock and chatter.
Traction/Sole Quality
The Thraxis have a really nice sole, which looks and feels like it's really high quality. It feels like rubber all over and feels grippy to touch and to walk in. Moderate pattern variety and average tread depth.
Reduced Footprint
I would call them average. While the sole's length is longer than average, they also have longer than average toe/heel bevel, which helps reduce the chances of boot drag. They balance out to make it middle of the road in terms of its footprint size.
Entry/Exit
It required a bit of force to get my feet into these. A good push. Not like “will I actually get into them” hard, but required a bit of force. And I’d made the effort to open them out as much as I could.
Liner: They don't have a liner lacing harness. But they do have Velcro at top on both sides. And I found those sides don’t have any chance of overlapping in the front, which is good (even if you've got skinnier legs than me, you should be good there). Then there’s also a third Velcro strap that wraps around over the top to make it more secure there. Given there’s no lacing harness, I like this.
And of course that third BOA (the one on the outside side of the boots) tightens the liner harness that wraps around the ankle of the liner.
Shell: Then the shell is just the inner side boa to tighten the lower portion and the front boa to tighten the upper portion. So nice and easy and relatively fast to do.
Score Breakdown and Final Verdict
Check out the breakdown of the score in the table below.
| Factor | Rating (/5) | Weighted |
|---|---|---|
| Carving | 5 | 30/30 |
| Slow Speed Response | 2.5 | 2.5/5 |
| Traction | 4.5 | 13.5/15 |
| Heel Hold | 4 | 8/10 |
| Adjustability | 4.5 | 9/10 |
| Shock Absorption | 4 | 8/10 |
| Reduced Footprint | 3 | 6/10 |
| Comfort | 3 | 6/10 |
| TOTAL (after normalizing): | 88.3/100 |
The Thraxis are stiff boots with a lot of support for high speed riding and aggressive, high angle carves. They don't feel so good at slow speeds and can be difficult for things like ollies and butters and overall board feel wasn't great.
Decent shock absorption, plenty of adjustability and really good heel hold.
Comfort has a high degree of subjectivity most of the time, so it may not be the same for you, but I found that my feet were cramping in these boots and I had quite a bit of discomfort from hotspots around the ankles. This would likely get better over time, but my experience with stiffer boots is that it takes more time for them to break in, so personally I would likely have a pretty uncomfortable time fully breaking these boots in.
More Info, Current Prices and Where to Buy Online
If you’re interested in learning more about the Thraxis, are ready to buy or want to research current prices and sizing availability, check out the links below.
If you want to see how the Thraxis compared to other freeride snowboard boots, or want to check out some other options, check out the link below.
Had a pair of Thraxis from ’20 and they gave up the ghost last season. They were overall a great boot. Bought a new pair this year, the ’24 version. Although they look extremely similar, they do NOT have the same performance. They don’t ride as stiff and the fit has gotten real loose.
I’ve never been a fan of BOA for primary laces and my old ones (with metal cables) required tightening more and more often to the point it was happening every run. Even replaced the entire cable and ratchet. But the new ones are now a synthetic cord and they’re not even making it a single run. When they are tight, these boots flex as much as my old ones with over 100 days. Seems like the boot is softer and the boa isn’t able to keep things in place.
Lastly, the same size doesn’t provide the same fit from old to new. The interior volume seems much bigger now, so I have to crank the boa way down before it snugs up around my foot. By that point the boot has become a foot torture device (old pair fit my wide feet nicely). At the top, the new liner closure strap is basically worthless because the liner tongue Velcros to the sides. Also, something changed with the geometry of the boot upper. It’s shaped like a cylinder – if it’s tight enough for the boot to engage above my ankle, then it’s absolutely crushing my calf at the top. Maybe if you have very skinny legs it’s less of a concern.
In any case, seems like something at K2 changed and it’s not for the better ime.
Best boot i have ever ridden, just now clapping out after a 100 days of heavy service, I think they may go another 20 days before they are done. Already bought another pair
Hi Nate,
I got the K2 Thraxis around Feb 2021, mainly based on your review. Almost two seasons in, they continue to serve me well, so thanks for another great piece of advice. Now, however, I have more questions on sizing…
The current Thraxis I have are US 10,5 – sizing down from US 11 Imperials, I probably didn’t dare to go smaller than that. I’m wondering, if for the next time buying new boots, I could go as small as US 10 on Thraxis?
– My foot length is 27,8 cm (with some chance for inaccurate measurement, but I tried at least not to go under the real measurement)
– The current 10,5, after having packed in (did not heat mold them) feel like there’s a little room in them around the foot.
– Standing up normally, the big toe touches the inside of the boot (relatively thick ski sock on), but there is no pressure whatsoever. Bending the knees, there is a gap in between the toe and the boot.
So while this size is “ok” to say the least, I wonder if I’d get an even better fitting / performing boot in size 10?
Having read the comments section, it seems that 27,8 cm foot should be pretty optimal for a 28 cm mondo shoe (which the Thraxis US 10 is claimed to be)?
The other consideration is getting an optimal fit with bindings. My current go-to binding is Burton X Est in size L, which I have to run the toe strap in the smallest setting. Still, there is some gaps between the strap and the boot, as well as between the sides of the binding and boot. This setup has worked for me, but if I were to buy a Burton binding again, would probably go for an M. More likely though, I’m looking to buy a Union binding next, e.g. the Atlas Pro or the Atlas FC. Wondering, if I could go for size M on those as well, even though Union bindings appear to run slightly smaller than Burton?
Thus, being able to size down on boots might make me a better fit with size M bindings as well?
Another question I have is that for 2023 K2 seems to have “Clicker X HB” version of the Thraxis as an option. What’s your view on that vs. the regular Thraxis, in terms of performance and fit (if there is any difference)?
Hi Jussi
Thanks for your message.
Firstly, in terms of the clicker HB, I haven’t tested K2’s clicker boots/bindings, so can’t really say anything there.
In terms of sizing, I think there’s certainly a chance you get into 10s for K2. I have a right foot that’s 27cm and left foot 27.3cm – and I find I can get in a k2 9.5. Bit of a squeeze to start but packs out nicely to fit well. I’ve always said that I would be perfect in a 9.75! I fit K2 10s the same way you fit the 10.5s essentially, once they pack out. I find that it’s fine but feel like there’s a little more space than ideal. I’m typically a 10 in most boots, but for some 9.5 works better for me – and K2 is borderline. Now, even though boots are designed with a mondo in mind, length of foot doesn’t always dictate the same fit. Some with my foot length might still have to go to a 10 everytime and some might fit a 9.5 well from the getgo. In your case, like me, your mondo is 2mm less than the suggested mondo of the boot. If you’re experience with a 10 is like how I experience a 9.5, then I’d say you could get away with a 10. It would be a more painful and probably longer break in experience (which you could speed up a bit with heat molding – and heat molding with a toe cap might be a good idea too) – but over time could be a really good fit. No guarantees as, like I said, length isn’t necessarily the most accurate predictor of fit.
With your current 10.5s, I think you would fit fine in a Burton M but I wouldn’t put it in a Union M. I find with bulky 10s that they can be maxing out the toe strap length on M Union’s. With a 10.5 I’d want it to be quite low profile, which the Thraxis isn’t, so I think there’d be a good chance your Thraxis 10.5 wouldn’t fit a Union M well (as in you might be able to do up the toe strap but it would likely not be able to be centered around the toe of your boot, which could cause pressure points). If you were to get in a 10, then I think you’d likely be good in a Union Atlas Pro or Atlas FC M.
Hope this gives you more to go off for your decision
I love these boots and it’s time to replace them. This is my second pair – I get about two seasons before they’re too soft and packed out. No complaints though! Every other boot I’ve used has been a floppy noodle after one season.
Have you been able to compare the 2022 Thraxis with the previous version? Definitely looks like they made some changes…
It’s the only boot for me, so I’m hoping the shape hasn’t changed on the newer version.
Hi AK
Thanks for your message.
I don’t see any major changes between the 2021 and 2022 models and even the 2020 looks to be pretty similar based on paper. I haven’t tested the 2022 model (harder for me to test boots as I have to buy them, test them and on sell them, so I only re-test if there have been major changes). But on paper they look very similar. I think the biggest change, from the looks of it, from the 2020 to 2021 model (and also on the 2022 model) is that it got the H4 Boa, but that shouldn’t change the performance of the boot – it just makes it harder to break the BOA cables or coiler (i.e. the coiler is designed to pop off on hard impact).
From a specs perspective everything else looks to be the same. From a visual look at them, the sole looks a little different, but I think that’s mostly aesthetic. But of course, if there are other changes that I’m missing, I’m more than happy to be informed. But from what I can tell, they’re not too different.
Hope this helps
Hi Nate,
Found a 2020 model with the H3 Boa for about $70 less than the current year with H4 Boa.
Since the season is over, and you have tested more boots since this review/last reply…
Wanted to ask, in your experience and opinion, if H4 Boas are “better”/bring enough improvement to the table to justify the price difference?
Thanks!
Appreciate all the reviews you do!
Hey Frank
Thanks for your message.
The biggest difference with the H4 Boa is that it pops off when there’s enough force. So, instead of breaking it just pops off – and then you can re-install and carry on. In terms of actual improvement to how the BOA works outside of that I haven’t noticed any difference. I think the biggest complaint people have with BOA is how hard it is to repair if it breaks – so, from my perspective, the idea of developing the H4 is to remove this weakness. Personally I’ve had a really good run with BOA and haven’t broken one yet, but I have heard of people who have – so that’s the biggest advantage of the H4 from what I can tell – they don’t feel smoother or faster or anything like that compared to the H3 – at least not from what I could tell.
Hope this helps
Hi Nate,
Sorry for taking so long to respond! I went through last season with the old pair and was definitely suffering by the end of the season. Lol. This summer I found a place online offering the 2021 year boots at a deep discount so I ordered it. Unfortunately they sent me the 2023 model (same as the 2022 I was asking about).
I haven’t been able to ride this yet, but just from trying them on and playing around they are definitely quite a bit different:
The liner fit is potentially better for me. I needed a heel wedge in the old model under the insole to get my ankle bones to line up. Fits perfect in the pocket now.
The inner boa plate no longer has a velcro attachment to the shell. I can see that being better as it can re-center itself each time you put the boot on.
Boa cables on the new model are composite versus metal in the old ones. Never broke a metal one…
Flexing in them they feel softer off the bat. So that’s a bummer. No weird pressure points but that added flex is concerning none the less. If memory serves the old thraxis felt crazy stiff when you first put them on but would soften up quite a bit after 10 days or so. If the new ones don’t break in at all (or very much) I’ll be happy. But considering I’ve never had a boot maintain the exact same flex, I’m guessing these are good for a season (80 days or so) before they are too soft. I’d love to be wrong about that, considering how expensive these are.
Anyway long story short – they fit different and are softer now.
I’ll check in mid-season and update.
Cheers,
AK
Hi AK
Thanks for the update and the insight. Very helpful. Look forward to hearing how you get on, once you’ve had a chance to give them a good run.
Hi Nate,
Welp, after 5 long days on the hill, I hate the new version! All because of the liner change. They added J-bars to the ankle pocket and they push WAY too hard. I am actually getting bruising there. It’s weird because I never noticed this at all flexing them in my living room – in fact they felt very nice. It wasn’t until I got on the mountain that I noticed them destroying my ankle bone area. I totally would have bought these in a shop just based on how they initially feel. But after literally 50 yards of riding I was thinking these were the worst boots for pain I’ve ever experienced. I hoped this would break in but it doesn’t seem to be getting better. I also tried heat molding but it didn’t effect they J bar foam.
Strange for K2 to make such a drastic change.. On the old ones I had to add j-bars to the ankle pocket. Seems K2 went too far in the other direction.
I now have some Tridents on the way (I’m a triple boa addict now). While waiting for them I’ll ride the Thraxis with my old liners in them. I also reached out to K2 to see if they can hook up a pair of liners from the previous Thraxis. I don’t have much hope for that.
Ah well. Moral of the story is once you find your perfect boot, buy an extra pair or two for when it gets discontinued.
Cheers!
Hey AK
Yeah, definitely an idea to buy extras if you find your perfect boot. Before I read the end of your comment, I was going to say to maybe try to get different liners from K2 to see how they go. Hopefully they can – and if not, hopefully the Trident’s fit you better.
Hey Nate,
Adding more comments here to keep the info flowing. Tridents fell through, as did an old liner from K2, so I decided to make these expensive boots work with some boot fitting. A wedge under the insole under the heel and then some additional break-in has pretty much alleviated the heel pocket pain.
There was also a weird instep pressure that started happening around day ten. Checked out the liner and I could clearly see spots where the shell was hitting weird. I used some boot fitting foam to spread that pressure out.
The boot is miles better now. Not *perfect* like the old Thraxis, but definitely liveable.
Longevity-wise I think this boot will hold up. I have around 30 days on it and the shell flex is very similar to day one. So, even though they started softer than the old thraxis did on day one, the materials seem to be holding up better.
Cheers and hope your season is going well!
-AK
Hey AK
Thanks for the update and great to hear you’ve been able to make them work – some nice innovative thinking there to get them to work for you! Hope your season is going well too!
Hi, I read a few of you K2 boot reviews and the sizing thing always comes up. My current Burton Ions are shot and I am considering Thraxis as a replacement. My Ions are a size 10 and fit perfect, toes just brushing, super comfy. This has been the case for any other burton boots I’ve had. So, size 9.5 in the Thraxis?
Thanks.
Hi JP-OH
Thanks for your message.
K2 boots are tough for me. I feel like the 10 is the perfect fit, as it was for the Thraxis, when I tested them. But I’ve also ridden 9.5s which have felt tight to start but have packed out well to a point I think they would be the better option long term. It’s really hard to say, because the Thraxis felt so good in the 10 for me. But other K2 boots have started to feel a little too big in the 10 after heat molding and riding for a while (e.g. K2 Ender). I rode the K2 Darko in the 9.5 and that felt like it was too tight to start, but started to feel good by the time I’d done a couple of laps and after heat molding.
Note that I didn’t heat mold the Thraxis before riding. I typically do, depending on the initial fit. The initial fit with the Thraxis was so good that I didn’t feel the need to heat mold. And also I’d ridden the Ender not long before and had heat molded that and felt they were starting to pack out a bit too much by the end of the testing.
My instinct is that if you’re a 10 in Burton, then probably a 9.5 in K2. For something like the Thraxis, it will take longer to mold to your feet (being stiffer), but I think in the long run, it’s probably going to be the better fit. I would heat mold if you go with the 9.5 though, to speed up that break in process.
Hope this gives you more to go off for your decision
Thank you for pointing out the bevel edge as it affect toe drag more than you would think. I also find a few bindings having to big of a pad these day so that the bindingpad actually drags.
Anyhow, I have a question I would appreciate your input on. My feet are 28,3 and 28,5 cm long. I have been riding mondo 29cm (US 11), but want to see if it is possible to squeeze myself into a pair of Mondo 28,5cm. I see that you normally ride 0,5cm Mondo more than your feet. Do you think it’s doable? I can live with some temporarily pain hoping they would pack out.
Ride or K2 would probably be the brand as Adidas and Burton don’t fit my feet very well. I am in the toedrag club so going down half a size would greatly improve on drag. Due to Covid there is not a lot of K2 / Ride boots to try on in the shops so I would have to order from an international webshop, which makes return quite a hassle.
Hi Boarddude
Thanks for your message.
I find I can squeeze into a 9.5 K2. It’s tight, but it does work and not to a point of being painful and gets better as I ride. I would probably go 9.5 if I was to buy K2 boots. 10s work well for me for testing, because I’m not riding them for that long, but if I was to buy K2, I’d go 9.5. I don’t think I’d say the same for Ride. I feel 10 is right for me there, but I haven’t tried a 9.5, so it could be possible. Note though that my longest foot is 27.3cm. So I sometimes get into a mondo 27.5 (K2, Salomon, Adidas) but there is a couple of mm difference, with you at the 28.5cm trying to get into a 28.5. It’s certainly what they’re designed to do, so I don’t think it’s undoable. In my experience with those brands I can do it (allbeit 2mm off the mondo). If you were to try I would go K2 rather than Ride though.
Hope this helps
I am very confused of the length measurements.
You use Burton 10.5 US and K2 10 US in all reviews (so they are comparable regardless of the number on the label).
Why does Burton have an good footprint reduction (4points) while k2 only 3 points?
In your trials; Burton imperial outersole 31.1
K2 maysis outersole 31.2
Is a millimeter worth a point?
Hi J.p
Thanks for your message.
I would ride Burton 10s, if I was to buy them. I rode the 10.5s for testing, which was fine, but the 10.5s would pack out too much over time for me and end up being too big. For testing I’m not in them long enough for them to pack out that much. The Footprint reduction scores take into account the difference between mondo and outersole. I do agree that 1mm wouldn’t be worth even half a point, but it’s technically 6mm difference size-for-size. Also, it’s worth noting that Burton boots have a lot more toe bevel on their boots than every other boot I’ve measured/tested, which allows for a greater angle before boot drag occurs. Hope that makes sense.