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.
Boots: K2 Thraxis
Price: $479 (USD recommended retail)
Flex Rating: Stiff (10/10)
Flex Feel: Stiff (9/10)
Rating Score: 93.2/100
Compared to other Freeride Boots
Out of the 19 freeride boots that I rated:
Overview of the Thraxis’s Specs
Check out the tables for the Thraxis's specs.
Freeride or hard charging all-mountain
A little heavier than normal
Who are the Thraxis Most Suited to?
The Thraxis are for anyone of an advanced level, looking for a stiff boot for bombing, carving and freeriding.
Especially suited to those who like boa - there are 3 of them after all! And need boots that help with heel hold.
Matches best to stiffer boards/bindings.
The Thraxis in More Detail
O.k. let’s take a more detailed look at what the Thraxis are capable of.
Boots: K2 Thraxis 2020
Size: 10 (US Men's Sizing)
Date: February 14, 2020
Conditions: Hard packed. Definitely not icy though. Just nice.
Off groomer isn't ideal but certainly doable. Again firm, but not icy.
Sunny and perfect vis.
Supposed to be -4 and -10 with wind chill, but feels much warmer than that. Probably cause it's so sunny
Was fresh snow overnight but not obvious when actually riding. But still pretty darn good. Can't complain
Bindings angles: +15/-15
Board Demoed With: Rossignol One LF 2018
Bindings Demoed With: Burton Malavita
Outersole Length: 31.2cm (mondo 28cm)
Difference between Mondo & Outersole: 3.2cm
Backstay Height: 27.5cm
Weight: 1140 grams*
* Average of a sample of boots I weighed was 1006 grams, so a decent bit heavier than the average, but pretty close to average. Heaviest were 1320 grams and lightest were 740 grams. Stiffer boots tend to be heavier, so for their flex, they are normal.
Not quite as stiff as the Ride Insano or Burton Driver X that I rode the same day, but still quite stiff. One of the stiffer boots I've ridden still, but just a notch down from those 2.
Width: Medium width. Not particularly wide, but not overly narrow either.
True to Size?: I usually ride a 10, and these felt really good in the 10. So, I would say true to size.
High or Low Arch: Snug on the top of my feet like they should be, but not painful, so I'd say medium in terms of arch. My right foot has more arch than my left, which is quite flat, so this is going off my right foot.
Really nice in terms of bombing and getting that quick turning at speed. And in terms of being able to hold carves nice and deep and long. Made my board more carvy than it otherwise is.
What I really liked is that it felt like I had to put in less energy to get that energy out of them vs other boots with a similar feeling for carves. And a little more maneuverable at slower speeds than other boots with a similar flex.
Really good in terms of heel hold. I had very minimal heel lift, and only noticed it when I was really trying to notice it.
Having that third boa that cranks on the liner around the ankle also meant that you could very easily crank down on the ankle if you felt like the heel was starting to lift a little more after riding for a while.
Really good adjustability on these boots. There are two boas that work on the shell of the boot. One controls the upper section and the other the lower section. So you can tighten those areas differently.
Then there's a third boa that cranks down on the ankle around the liner of the boot. Because that is controlled from a boa coil on the outer boot, it's super easy to adjust that on the fly, without having to open your boot right out, which I really like.
Let’s Break up this text with a Video
Nice comfortable feeling, plush liner. And overall very comfortable.
At first I had pressure on my inner ankles. But that pressure was greatly lessened from heat molding and then even more so just with a walk from the car park to the lift. By the time I started riding, it was barely noticeable and after a couple of runs was all but non-existent. So, just something that took a bit of breaking in, as is often the case with any boot, but particularly with stiffer boots.
No cramping at all, which is one of the biggest things I look out for in boots.
Decent shock absorption for flat landings and absorbed chatter pretty well too.
They have quite a rigid firm sole and a good tread depth. Nice for traction but not so much for board feel. And stiffer boots tend to be not as good either. All that said, they weren't terrible in the board feel department, but also not amazing. A little better vs the Ride Insano. About the same as the Driver X.
Sole is really high quality, firm and good tread depth. Felt good walking in them. Didn't have anything too technical or icy to walk in - just the car park and up to the lift, but from sole inspection, I imagine they would have great traction.
They aren't super bulky, but definitely not low profile either. A little longer on the outersole vs mondo than the average.
Easy enough to get foot in and out - and easy to work with the boas. A little longer than something like a single boa, naturally but still fairly fast.
Apart from the 3 boas, there's also a velcro strap that tightens around the top part of the liner. This is another little step, but doesn't take long and gives a nice secure feeling around the shins.
Score Breakdown and Final Verdict
Check out the breakdown of the score in the table below.
TOTAL after normalizing
The Thraxis are my personal favorite freeride boots. Nice and stiff and responsive, but with just enough feel for them and without having to put too much energy into them vs other stiffer boots.
And I really like the triple boa system on them - and just all round comfortable with great heel hold and no real weaknesses at all, but with a lot of strong points.
Just really nice boots to ride in that give nice spring, energy and power.
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, or want to check out some other options, check out the link below.
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)?
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.
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
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?
Appreciate all the reviews you do!
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
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.
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.
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.
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.
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!
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 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.
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?
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.