Mavic Ksyrium Pro Thermo shoes

Mavic's Ksyrium Pro Thermo shoes are almost fantastic – they're warm, comfortable, easy to slip on and off, and decently stiff for pedalling. Unfortunately, the waterproofing only works to make things worse, as heavy rain or spray quickly makes its way in and then can't get out. For cold, dry rides they're excellent, but that's obviously way short of what Mavic promises.

Early in this test, I hobbled indoors, let my sopping socks splat to the floor and poured a tablespoon of water from each shoe as my toes cold-welded themselves to the floorboards. Let me tell you, my wife was as delighted as I was.

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Mavic says the Ksyrium Pros "simplify your winter weather setup without having to wear booties over your shoes", but in that they fail. And that's a shame, because in every other area (all the dry ones), these shoes are great.

The sizing is accurate for a close but comfy fit in thick socks, which is good as the entire upper is pretty rigid and will not give. A large rubber bumper protects the toe, and they feel substantial enough to actually protect your feet in a crash (and also to survive it in pretty good condition).

Non-replaceable hard rubber bumpers protect the toe and heel from wear while walking, and the sole features wide, raised alignment marks that actually work.

The Ortholite insole has good arch support and no pressure spots that I encountered. The only issue you might find is if your feet are particularly wide, as these are on the narrow side and, as I said, pretty unbending.

The single Ergo dial cinches a well-padded tongue down comfortably and with excellent security, and there's lots of room for getting in and out – the splash cover zips up tightly once you're in, before two large, well-positioned Velcro tabs seal it around your leg. There's a bit of stretch around the top, so they feel unrestrictive and getting a tight seal is easy. It's just a shame it doesn't work.

Even with the cuffs done up tight and hidden underneath full-length tights, rain and heavy spray soon makes its way in. Wet roads under clear skies will have your feet noticeably damp and cold after 10 miles. An hour of normal rain is enough to leave you with socks like you've walked into the sea. An admittedly horrible storm with sheeting rain and level-with-your-pedals floodwater filled them with water that then couldn't get out.

Clearly rain isn't getting in through the bottom, despite what look like (blocked) vents in the heel and toe, or through the side of the upper, despite surface perforations to allow the membrane to breathe. Otherwise it would drain out. The Gore-Tex outer and efficient nylon-fibreglass composite sole – which is surely being braced for extra stiffness by that rigid-sided upper – do a great job of being impervious.

> Buyer's Guide: Essential wet weather cycle clothing and gear

I'm actually a little mystified as to how these so squander that Gore-Tex membrane and emerge quite so vulnerable to water. Mavic says the neoprene ankle cuff is only 'water-resistant', so perhaps water is actually soaking right through your instep and/or the rear. A quick and dirty test pooling water inside the cuff saw nothing soak through within a few minutes, but just how resistant it is depends on the size of the gas bubbles within the fabric itself. Mavic doesn't specify that. It's possible the cuff will wet through with longer exposure, but post-ride everything's equally soaked, so I can't say for sure.

One last problem, presumably a result of the insulation, is that the Ksyriums take ages to dry. It took two days to get them dry after that storm, and at least 24 hours after more normal rain. They're not ideal for multi-day rides.

Avoid water that's either falling or just lying around on the road looking for a toe to freeze, and everything is admirable – the build and finish are excellent, with the complex pattern of fabrics and shapes having been sealed together with impressive accuracy and strength. Details, such as the large textured rubber gripper on the Velcro, the quality of the dial and the subtle reflective highlights, impress. On dry rides they're great.

> How to keep your feet warm while cycling in winter

Unfortunately for the Ksyriums, there are more effective options available for similar money. Northwave's excellent Flash Arctic GTX winter boots are £210 and as waterproof as you can realistically expect, while Fizik's Arctica R5s are £190, warm and – yes – waterproof. In fact, Northwave's fantastically warm, £140 Flash TH winter shoe appears to cope better with water than the Kysriums, despite lacking any sort of cuff or claims beyond mere water repellence.

If you live somewhere that's regularly cold and dry, the Mavic Ksyrium Pro Thermo shoes will make your riding far more pleasant. If, however, there's any chance of water during your rides, the Pro Thermos will be unable to keep your feet either dry or warm.

Verdict

Warm, comfortable and really well made winter shoes, but definitely not waterproof