Aku Serai Boot Review

30th Jan 2018

Aku Serai Boot-2

I have now tested a range of Aku footwear and know their last suits my mid to broad foot perfectly.  So I had high hopes when invited to test their technical mountaineering and ice climbing Serai model.  In this category my previous experiences have predominantly been with La Sportiva and Scarpa products and so I wondered how the Serai would compare.  I have been using the Aku boots in Scotland for a range of winter activities and for ice climbing in Norway.  Here are my thoughts.......


You are going to notice two things when you first spot a pair of these on the shelves of your local climbing shop.  First, they are a very attractively styled boot.  I have always thought Aku nail it with the appearance of their footwear and the Serai follows that pattern nicely.  It mixes understated black with orange detailing and silver flashing and reinforcements in key areas.  It looks great.  The next thing you’ll notice happens when you pick the boot up - the Serai is seriously light at 840 grams per half pair.

Beyond that, the next features to detail are around the materials and construction.  For the Serai uppers Aku use a mix of hardwearing Kevlar with nylon reinforcements in key areas and then a broad PU rand wraps around the boot and there is a stretchy microfibre tongue.  The upper boot material spec then finishes off with a Goretex liner and a layer of Primaloft insulation.  

The lacing system varies up the length of the boot.  Around the toe box there is a couple of flat tape eyelets which minimise snagging and then there are a couple of roller eyelets before a single locking eyelet at the top of the foot section.  After this a cord loop set back towards the heal is designed to pull the foot firmly into the heel cup and finally there are a couple more traditional style hook fasteners.  At the top of the boot there is an elasticated Velcro closed debris gaiter that snugly seals the top of the boot to the ankle.

In terms of the sole system, Aku have combined a Vibram Nepal outsole and then, to get the required stiffness for this to be B3 boot, Aku have used a carbon PU dual density exoskeleton midsole and carbon fibre, honeycomb aluminium and eva microporosa lasting board.  It is a comprehensive package!


I was a 16 year old scout and had just started exploring the winter mountains.  We had visited Snowdonia and had made a trip to the Lake District but nowwe were heading a lot further north.  The delights of Glencoe awaited.  We had cobbled together enough equipment but, with our climbing aspirations, one significant hurdle remained - our footwear was definitely not up to the job.  At the time we simply didn’t have the funds to buy one of the limited options in our local climbing shop. 

I ended up borrowing some stiffened plastic boots from a family friend and within a day my feet raw mince.  Some of my friends got by using their normal inadequate boots and it was only Neil, with his powers of persuasion, who had managed to get his parents to loan him the money to buy some ‘proper’ footwear.  The boot of choice at that time was a leather beast called the Galibier Super Guide.  These were an incredibly solid leather boot with rigid sole and handmade by a French bootmaker.  My friends and I regularly stared jealously at Neil’s boots which, while we suffered constantly, kept his feet warm and dry.

I had no reason to imagine Neil still had the Super Guides, but when I visited him at Christmas and we got on to reminiscing about those formative years, he disappeared off and, after a bit of a rummage in his cupboards, returned with the boots in hand.  They still looked like new and also, by today’s standard, looked very old fashioned.  But the progression in technical winter boots really struck home when he dropped one into my hands.  The Super Guides weighed something over 3kgs a pair and that, compared to what is on the market now, is such a lot to slog up a hillside.

The Test

Aku market the Serai as a boot suitable for rock and ice fall climbing and activities in high elevations.  So, the test for these incorporated time spent climbing ice falls in the cold and dry conditions of Norway through to Scottish winter days offering a typical mix of conditions - from wet snow and stream crossings through to deep powder snow and climbs comprised of ice and neve.  


I have now tested a range of Aku footwear and have never been disappointed.  Aku maybe a brand unfamiliar to some in the UK but don’t let you put you off - they have a long pedigree and, as specialist footwear manufacturers, their whole focus is on quality footwear.

Aku are an Italian based footwear company whose headquarters are in the famous technical footwear producing Montebelluna district. The company was founded by Galliano Borodin and has, over several decades in business, grown from a small workshop to a huge industry.  Even so, all their new styles are still manufactured in Europe with over 90% local raw materials and a 100% traceable supply chain.  An enviable business model.

In Use

I asked Aku to send me a pair of Serai’s half a size bigger than my normal boot size allowing for some thicker socks and to ensure enough room in the toe box when kicking crampons in. This turned out to be a good call and, straight from the box, these boots have offered fantastic comfort (see my thoughts on winter boot sizing in the paragraph below).  

I know the Aku last suits my foot shape and this is always something potential buyers would want to check for their own feet, but pulling these on for the first time felt very much like pulling slippers on.  I wore my normal winter sock set up of a skinny liner sock and chunky wool top sock and the boots were immediately supportive and yet snug fitting - and this is before I had even laced them up!  

This comfortable fit is due in part to the foot shape but also very much to do with the microfiber tongue unit.  I had previous experience of this on the Aku Alterra GTX boot I reviewed here and guessed it would work as well again on these.  The tongue design is stretchy and, as you push your foot in, it will stretch to accommodate that while then stretching back to hug your shins.  It makes for a really comfy fit and also has the advantage of offering very little bulk so there aren’t bits of tongue material to tuck out of the way when you come to lace the boots up.

I’ve explained the lacing set up above and it works really well.  The inset heel lock eyelet in particular pulls the foot securely into the heel cup - I have used a similar system on a few other pairs of boots and rate it highly.  The only eyelets I am less keen on is the top two which, because they are quite a defined hook shape, are prone to catching on gaiters or overtrousers.  It isn’t a big problem - just worth being aware of.

So, with the combination of the stretchy tongue, well considered lacing system and Aku’s well shaped last and footbed, the Serai’s offered a brilliant fit straight out of the box and I haven’t had any problems with comfort even during some long mountain days.  The fit is also very secure and I have had absolutely no issues with heel lift even when front pointing on steep ground or when ascending or descending steep ground on toe edges or sides.  They offer a very precise fit.

The Serai’s are fully stiffened and you can use them with any crampon style.  I have used mine with both Grivel Airtech’s and a full clip in Petzl Lynx which, because the Serai’s have a defined front and rear welt, felt very secure.  I have used the boots on routes up to WI5 and they have felt comfortable during long front point sessions.  

The Serai’s combine a durable PU rand with nylon reinforcement patches at the toe and around the heels and lacing and then use a Kevlar fabric for the rest of the upper.  I have used the boots for quite a number of winter days but I won’t say this is a long term test.  I can definitely say, however, that a mix of steep ice fall climbing, mixed climbing and winter walking and mountaineering haven’t put so much as a mark on the Serai’s.  In terms of durability the Nepal Vibram sole unit is also worthy of mention.  It is holding up to wear and tear brilliantly and has performed well on all terrain - it has deep lugs that grip well but also shed snow easily.  The Nepal unit also offers the option to resole the boots if needed.  So, in all ways I consider the Serai a durable boot and think any user will get a great lifespan from them.

I have used the Serai’s for days in deep powdery snow in Norway and for slogs through boggy ground and slushy snow in Scotland.  They have proved to be waterproof and my feet haven’t become overly damp from interior moisture build up.  The waterproofness is likely to be a combination of the outer fabrics along with the Goretex liner and water resistant insulation.  I have now treated them a few times with Nikwax waterproofing and they are performing as well as new.  The Primaloft insulation is also a breathable material which helps wick moisture away from the foot.

A final vital consideration for winter boots is, of course, warmth.  Winter days often involve long cold waits combined with bursts of energy output where you are generating plenty of heat.  Aku have used low bulk Primaloft Insulation Eco which offers best in class performance for situations where repeated compression and durability are key requirements.  In practice, I have certainly been surprised how warm the Serai’s are.  I was concerned about using them in the -20 Celcius temperatures we faced in Norway and yet, although my feet were chilly at times, they were certainly as warm as boots of a similar type.  This is really impressive given their light weight.


Technical winter boots are one of the hardest choices an all seasons climber has to make.  They need to be warm enough, waterproof enough, light enough, durable enough, stiff enough and comfortable enough for all day comfort.  It is also a tough choice because this type of boot is an expensive investment and it is hard to assess all these qualities in the comfort of a shop. 

Many folk end up defaulting to brands they have used before because they like the fit and last shape although, for others, they have no prior experience to draw on.  It emphasises the need to get them fitted at a shop with knowledgable staff and also to choose a shop where you can try different brands and models on.

I tend to choose a slightly larger size in winter boots (usually a half size or, occasionally, I might stretch this to a full size larger). This allows for thicker socks and also offers a bit more space in the toe to allow room when kicking in with crampon front points or when descending steep ground - you’ll soon know about it if your toe is repeatedly hitting the front of the boot. 

Sometimes, however, if you leave room at the front then the boot feels sloppier all around.  However, this is where the importance of a good boot fitter comes into play because there are various ways the boot volume can be reduced.  Don’t give up....and don’t be tempted to get ones too small in the length because that is one thing that can’t be changed.


The Serai’s are a high performance and beautifully made winter boot from a long established dedicated footwear manufacturer with a great pedigree (please read the info about Aku in the paragraph above).  They look great, perform superbly and offer great value.  

I am also impressed how they tick the boxes for various users and so will really suit the person that wants a one boot option for a range of activities.  As always, they need to suit your foot shape and I strongly advise you getting them fitted by a specialist (see info on boot fitting in the separate paragraph) but, if they do, go for it.  The only remaining observation to make is that I reckon, at an RRP of £360, the Serai also offers great value for money in this category.  Details can be found on the Aku website here.  Please also watch the detailed feature run down in the UKClimbing video below. 

Posted by Paul

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