Giro Blaze winter boots review

Giro’s all-new winter MTB boots are packed with thermal tech, but does it work?

Giro Blaze MTB Boot review
(Image: © Guy Kesteven)

BikePerfect Verdict

Giro’s new Blaze boots are notably lightweight performance MTB boots that still keep your feet dry and warm in grim conditions but like most winter boots that comfort costs a lot and they’re better in cold, dry climates than relentless wet

Pros

  • +

    Stiff

  • +

    Light weight

  • +

    Stable and secure without hot spots

  • +

    Splash, shower and snow proof

  • +

    Warm when wet

  • +

    Good breathability

  • +

    Easy on/off

  • +

    Protected laces work long term

Cons

  • -

    Sizing up is wise

  • -

    Let prolonged rain in quickly

  • -

    Take a while to dry

  • -

    Cord-locks always loosen slightly

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The last Giro boot a few years ago was a big clumpy hiking boot with an open top and flexy walking sole, but thankfully the new Blaze is an entirely different performance shoe. It’s light. It’s usefully stiff and most importantly its multiple layers of thermal tech are well sealed, too. That kind of design and materials don’t come cheap though.

So how does it stack up against the best winter MTB boots on the market? Read on to find out. 

Design and aesthetics

The Blaze gets off to a powerful start by using the same nylon composite sole as the Rincon XC/Gravel race shoe, complete with steel toe stud blanks and stainless steel cleat hardware to reduce corrosion. While it’s mostly made up of continuous cutaway blocks rather than separate tread lugs, the dual-injected rubber sole is soft compound ‘Ice-Grip’ to help you stay on your feet whatever is beneath them. There are rubber protection panels at the toe and heel, and an anti-scuff patch on the outer forefoot where it overhangs the sole. You get reflective logos on the side and heel, too.

The whole upper is sheathed in a stretchy, waterproof and breathable seam-sealed shell fabric with a waterproof zip slanting up the front of the shoe to the high ankle cuff. This is backed with Primaloft fleece from the forefoot area backwards and upwards toward the cuff, and there’s a diamond padding over the outside ankle bone too. Inside this shell is an inner shoe with a cord-lock lace system over an extended tongue and with more Primaloft right through. The footbed has a high loft fleece face and a laminated foil layer to bounce radiated heat back into the shoe, as well as keeping the cold out. Despite all this, the Blaze still sits on the scales at a similar weight to a lot of standard trail shoes at under 900g even in a size 45. Bigfoots will be pleased that sizing tops out at 50, although anyone under 38 is really going to have to double up on their socks, unfortunately.

Performance

Sizing is the first thing to think about when buying these, not because it’s weird in any way, but because the insulation does take up some room, and if you’re a fan of thicker socks in winter and don’t want compromised circulation, then we’d go up a notch. If you like really fat socks then probably go up two, as there’s no flex in the sole to ease off the snugness and that zipped ankle is pretty tight to keep out water as much as possible. Having struggled in and out of various awkward-entry winter boots over the years, the big openings on both the outer shell and the inner shoe are massively appreciated. Especially when wobbling about on one leg trying not to step on sopping ground while swapping shoes before a ride. Having the laces hidden inside means that as long as you keep the zip clean, they’re easy to get off, too, with no chances of dials freezing solid or getting jammed with mud.

Once on, the cord-lock snugs the shoe up well enough to start with, but we’ve never had a cord lock that stays properly tight for long, and these are no different. The outer layer is stretchy enough to keep your foot snug rather than sliding around though, and the heel is well padded and structured to stop lift when things get too slippery or snowy to ride. There’s plenty of stiction in the sole, too, but if you’re regularly scrambling up really steep, sloppy slopes we’d definitely fit the optional studs for fang grip as the tread blocks don’t dig in much.

If you’re determined to power up stuff on the bike, the nylon composite sole is well up for handling a lot of wattage and you can keep on the hammer for hours without obvious hot spots over the cleat. That does mean less nuanced traction and trail feedback than a softer shoe, but means they’re great for fast trail/XC/gravel which is what their space age styling leans towards anyway. The low weight will also be appreciated most by fast riders, especially compared to the big, clumsy lumps wheeled out for winter by some brands.

In terms of weather-proofing I’ve been generally very impressed but they’re definitely inclined towards colder and snowy use than relentless wet weather. That’s because while the outer shell will gamely shrug off frozen puddle plunges, showers and snow, the 10k proofing rating will let water in faster than something like a GoreTex liner would. As tight as it is, the cuff can’t stop water from running down your legs or complete submersion completely either although it works great under waterproof trousers. Where the design really wins though is that the protection is right on the outside. That means there’s no soggy outer layer sucking out heat beyond a mid-layer membrane or getting in the way of breathability. So while the WVT breathability rating is a relatively low 10k, I’ve ridden hard for several hours in the Blazes with very little sweat build-up despite being soaked up top inside a very breathable Neoshell jacket. The shell also keeps wind out very well so in dry, cold conditions, they’re awesome. 

Even when prolonged rain has gotten through the shell or sneaked in from the top, they still stay cosier than any other lightweight boot that I’ve used, and the thermal insoles are particularly effective if you’re off and walking regularly. If you’re not providing the thermal pressure to shift moisture outwards, the thick fleece liner does take a while to dry though, so if you’re riding every couple days we’d definitely recommend getting a boot dryer of some description. At £210 RRP, you’ll need to be riding regularly in grim conditions to make the investment worthwhile too although they’re mid-pack in terms of the prices of their obvious competitors.

Verdict

I’ve never ridden a boot that is guaranteed to keep you dry and warm whatever the weather, but the Giro definitely extends dry, cosy comfort further into foul conditions than most. Its low weight and high stiffness makes it a great choice for high performance riders and the stretchy external shell is impressively snow- and splash-proof. Even when they wet out eventually, they stay comfortably warm right down to freezing point, but they’re not excessively sweaty if you’re working hard or it warms up unexpectedly. I’d definitely suggest sizing up for toe wiggling and easy blood circulation though, and they’re not as waterproof as Gore-Tex membrane boots.

Tech Specs: Giro Blaze MTB boot

  • Price: £209.99 / $TBC
  • Weight: 880g (size 45 without cleats)
  • Sizes: 40 - 50
  • Colours: Black only

Guy Kesteven is Bike Perfect and Cyclingnews’ contributing tech editor. Hatched in Yorkshire he's been hardened by riding round it in all weathers since he was a kid. He spent a few years working in bike shops and warehouses before starting writing and testing for bike mags in 1996. Since then he’s written several million words about several thousand test bikes and a ridiculous amount of riding gear. To make sure he rarely sleeps and to fund his custom tandem habit, he’s also penned a handful of bike-related books and talks to a GoPro for YouTube, too.


Rides: Pace RC295, Cotic FlareMax, Specialized Chisel, Vielo V+1 gravel bike, Nicolai FS Enduro, Landescape custom gravel tandem

Height: 180cm

Weight: 69kg