Custom-fitting bike shoes aren't new. A number of small companies specialise in bespoke bicycle footwear, but nearly all of the available offerings are tricky to get hold of, involve a long wait and will part you from a very sizable lump of money. Lake pointed the way last year with its heat-mouldable carbon fibre shoes, which let you pop the shoes in an oven and then mould the heel and sides to the shape of your foot.

Now Shimano has developed the heat-moulding idea a step further, bringing it closed to the full-custom fit offered by the companies that make shoes based on a plaster cast of your feet. The M300 (and its R300 road brother) is the first shoe to feature Shimano's Thermo-Form technology, marrying a carbon fibre sole to fully-mouldable uppers.

At first glance the M300s look like Shimano's other high-end shoes - one ratcheting strap, two Velcro ones, mesh ventilation, chunky tread with studs under the toes. Rather than just sticking them on your feet and doing them up, though, these take a little while to get right. Fitting involves heating the shoes in an oven and then using a vacuum pump to squish them on to your feet - you'll appreciate that your best bet is to visit one of the bike shops that have the necessary equipment and expertise (have a read of this earlier article for the full low-down on the fitting process).

On our first ride, we thought for a while that Shimano had made a bit of a blunder here. The shoes weren't merely snug, they were actually too tight. But with time, two things happened - the uppers "gave" a little, as all shoes tend to do, and we realised that we didn't have to do them up as tight as regular shoes. Because they're shaped to your feet, they rely less on the fastenings to stay put. We've been using a couple of clicks less than on other Shimano shoes on the ratchet strap and not pulling on the Velcro at all.

Since they've bedded in, the M300s have joined Specialized's BG Pro shoes in pole footwear position. We're finding it hard to decide which is our favourite. The M300s are super-comfy, but if you've found shoes that fit your feet anyway it's not a huge leap forward. And they're quite pricey.

It's certainly great to be able to combine a super-stiff carbon sole plate with very comfortable uppers. There's one small niggle with the carbon soles, though - there's no tread under the arch, just plain carbon (not even the thin rubber layer that many shoes have), so if you ever find yourself briefly parking that part of the foot on your pedal you'll probably experience slippage.

Ups and downs

Comfiest shoes ever, ultra-stiff pedalling platform

Expensive, sketchy if not clipped in, looks possibly a bit "disco slipper" for some

Verdict

The benefits of a shoe that fits perfectly are clear. But just like full-custom frames, for most people it's a small benefit - it's there, but it's small, and the closer you are to the tall bit of the bell-shaped curve the smaller the benefit is. The M300s are lovely, super-comfy shoes, but expensive - we hope to see the same technology in more accessibly-priced shoes in the future.

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