Shimano’s GF8 is a flat pedal shoe with a difference, it’s a pumped-up shoe/ankle boot hybrid with extra insulation and a waterproof/breathable liner to make it winter-ready. With not that many wet/cold-specific flat pedal shoes on the market the GF8 is well pitched and, together with a brand new rubber compound on the sole, Shimano hopes it can compete with some of the best mountain bike shoes out there.

The Shimano GF8 uses BOA retention for a snug fit, with no need to handle soggy laces

Details and Specification

One of the first flat pedal shoe manufacturers alongside Five Ten to really catch on, Shimano has a long history in the MTB footwear game. 

The GF8 continues that tradition with a futuristic no-lace design using a BOA dial and wires to tension it and hold the shoe onto your foot. But the really big change is the brand has updated its latest flat pedal line’s Ultread sole compound with a new Gravity Flat (GF) rubber formula. This blend is in other flat shoe variants, but the GTX sole here is slightly different again and optimised further for colder weather to retain stickiness and grip.

Ultread GF is the new Shimano tread compound, and it is genuniely a huge improvement in grip and feel

Shimano has meddled with sole compound multiple times over its two decades or so in the flat pedal game and worked with leading rubber manufacturers and partners like Vibram and Michelin along the way. This Ultread GF formula is by far the stickiest and grippiest I’ve tried to date though, and together with a tread of tightly packed hexagons in the pedal zone and more open shapes to aid walking traction, the sole here is well designed for what you’ll be doing in it.

Smooth panels (with some perforations for ventilation) on the GF8 upper form a kind of wraparound design that covers most of the top and the BOA laces. Above this, the ankle and upper front foot is covered by an elasticated, coarse fabric cuff with webbed loops at the front and rear to help pull the GTX into position. The ankle cuff also has an elasticated collar to stop water and mud creeping in the interior that should be out of sight if you wear riding trousers (very likely in the conditions this shoe aims at).

Gore-Tex winter boots were once the preserve of clipped in riders, but the GF8 changes things

Taking care of waterproofing is a Gore-Tex liner sock that fully wraps the interior and forms a sandwich with an insulating fleecy layer to keep the chills out. This breathable liner extends all the way up to the ankle cuff to protect against splashes and rain.

Shimano’s toe box is reinforced to resist stubbing and strikes, and its midsole is cushioned to isolate feet from vibrations and impacts. That said, the GF8 shank is on the thinner side and not as supportive and isolating as Specialized 2FOs or Ride Concepts shoes I ride in a lot. There’s also less of a distinct position inside for feet to settle into and feel supported than with Specialized’s Body Geometry footbed shapes. 

If there’s one shoe I’ve tested that feels almost identical though, it’s the also relatively new Fox Union flat, where I’d argue the GF8 feels very similar in terms of sole feel, grip and the interior shaping.

The snug opening makes the boot comfy when on, but a real struggle to get them there

Performance

The first thing anyone is going to notice immediately is how hard this GTX shoe is to get on. With the small opening in the ankle cuff (that’s unfortunately not small enough to keep all damp and debris out riding) you really need to pull like crazy to get the GF8 to pop into place. 

Twin loops at either side of the ankle (webbed lengthways into the fabric upper cuff) help with the job, but I’m not exaggerating saying you better have eaten your spinach to get this shoe on over thicker socks. In this regard it really reminded us of the Only What’s Necessary FR-01 boot from 2017. Once in place, Shimano’s fit is comfortable though, and the GF8s feel snug and hot-spot free. The BOA dial is quick and easy to cinch to a preferred level of tightness and hold too.

Being so difficult to get on, on my first ride, I imagined I’d have an absolute nightmare getting the GTX off covered in mud and slime, but removal is actually way easier than installation, and so long as you press down on the back edge of the heel, the shoe comes off ok, which is essential at the end of freezing cold rides when you’ve had more than enough.

With the Gore-Tex liner pealing away inside the shoe, the GF8 is trashed

As mentioned earlier, grip levels here are totally sorted – there is no unwanted movement or slipping around on pedal studs, and the sole is also well damped, so vibrations and impacts don’t bounce or shuffle the shoes around too much; a trait older Shimano sole technology suffered too much of.

In terms of winter specific features, the sole never seemed to lose its effectiveness even on a sub-zero day, and the GF8s are almost completely waterproof against splashes and mud (with the only caveat that if it’s absolutely hammering it down, some water can enter via the ankle cuff that didn’t hug my leg quite tightly enough). 

Shimano’s shoe is warm too with a nice cosy feel on the coldest days, without being overly stuffy or boil-in-the-bag in the single-digit temperature days you’re most likely to be operating in.

Is there a way to make the opening secure and mid-proof, but still open wide enough to actually get your foot in?

So far, so good then, but (and it’s a massive but) the GF8 literally ripped apart in my hands after a handful of rides. The failure stemmed from the difficulty getting them on that means you’re really pulling hard at the rear ankle loop, and on about the fourth time, mid-pull and trying to install, a loud ripping sound came from the left shoe and the Gore-Tex liner tore away from the shoe’s exterior. 

Thankfully, I managed to coax the shoes on with some internal fiddling and wriggling as they were the only pair I had with me to ride in, but after that, the GF8s were toast and impossible to get on properly.

Subsequent pulling on the ankle loops just ripped the liner clean out of the heel portion of the shoe, and the Gore-Tex sock and insulating material from the back of the shoe has now ended up crunched up in the bottom of the footbed. If I try to wear the shoe, it bunches up under my heel to the point it becomes unrideable – all very frustrating for such a promising product costing over £200.

I might have got unlucky, but from the first try, it felt like this failure was something waiting to happen, and I’m not sure of the solution. Double or triple-stitching of layers and more reinforcement at the ankle cuff, or even a rear zip fastener might help, but anyone with any experience of zips on cycling overshoes knows only too well that they aren’t exactly renowned for long service. Any shoe fastening solution has to be bombproof in an area sprayed with all manner of wet mud and gunk for the duration of a ride.

The Shimano GF8 shows amazing potential, but we tore it to shreds insize half a dozen rides