Although winter mountain biking shoes are not a piece of equipment everybody will need due simply to the fact that most mountain bikers leave their bikes until warmer weather, those of us who do not want to stop just because the weather is bad have few options for keeping our feet warm and protected in such conditions. Honestly, I am not a fan of overshoes when temperatures drop below 10°C so a good winter MTB shoes are a must.
The Shimano SH-MW81 GORE-TEX shoes are an upgrade to their previous model the MW80 which up to now, was the only model Shimano offered for MTB shoes with cleats as far as I know.
These shoes are made from GORE-TEX, a water resistant and breathable fabric that is also windproof. I have tried regular winter boots just to find out that once your feet get wet from sweat or other source of water things go really bad really quickly. The idea behind GORE-TEX is to allow the extra moisture generated from sweating, to escape through the membrane, while keeping the water outside from getting to your feet.
The neoprene ankle cover is not that waterproof in my experience, although it has a splash guard that is, but it is a nice touch. There are 4 Velcro straps that allow a flexible fit and do not create any discomfort if properly adjusted.
As far as reflective elements go, you have the big silver strap on the front, a smaller patch on the side and the back. Positioned this way they provide almost 360° of coverage, no complaints here.
The fiberglass reinforced polyamide sole improves the power transfer to the pedals. I have not used these shoes without the cleats so no idea how will they perform on flat pedals. The mud shedding tread pattern works well and manages to stay pretty much clear all the time. The optional shoe spikes were not included in the box and are sold separately, a thing I did not expect.
One thing I really liked about the cleat mount was that it was lined and did not make the usual metal sound when walking. While some dealers include the SH-51 cleats in the box, I have replaced them with the Shimano SH-56 SPD cleats as all my other mountain bike shoes.
The inner shoe is fleeced with polar insulation which helps in keeping the warmth trapped inside the shoe. My only complaint is, that in the foot toes area there is not enough fleece and your toes will start to feel cold in temperatures below 5°C with a light weight merino socks, depending on your blood circulation. I have survived with a medium thick socks up to -5°C but my feet felt quite cold at the end of a 2 hour medium intensity ride.
As far as the sizing goes, my regular Shimano summer shoes are a size 46, so I ordered these in 46 too. For comparison I usually wear 44.5 Lacoste sneakers and 45 in other shoes. The Shimano MW81 are a bit roomier in order to accommodate thicker socks. While with light and medium weight wool socks you will have no issues, heavy weight wool socks might make you go a size up, depending on the size and construction of your feet. I suggest you better try them with the thickest sock you have before buying, just to see how they feel.
The bottom line is, these are great winter mountain biking shoes, warm, breathable and waterproof, although they technically are made from waterproof material and will protect you from rain/snow, riding through big puddles of water will not be so forgiving if done repeatedly. As far as appearance goes, they look a bit bulkier then your usual cycling shoes in the same size, but do not feel quite like that on your feet, weighting around 100g more.
Even though there are more expensive winter MTB shoes like the SIDI Diablo GTX and some cheaper models, the Shimano SH-MW81 GORE-TEX Winter MTB shoes, priced around 160-190 EUR are worth the money and you will be happy to have them in your winter arsenal for at least few years.
Tested with Shimano SPD pedals PD-M530 and PD-M780 and SH-56 cleats.