The MX331 is Lake’s flagship mtb shoe, designed for the race crowd looking for a performance oriented shoe. In line with their 2 top tier road shoes, the MX331 has some neat features and a fully moldable carbon heel counter.
Heat moldable shoes, whether partial or full, are nothing new, but few offer a moldable carbon option. It’s a wonder though that the tech for molding shoes didn’t come to the cycling market earlier than it did, as ski boot manufacturers have been offering it for many years. The carbon midsole and heel counter is all one piece, designed to increase stiffness and foot support.
Out of the box, the MX331 won’t wow the weight weenies, being a little more weighty than some other purebred race shoes, yet it is packed with features. The shoe feels substantial, like it could take a good a beating out on the trail.
The sole is an area where some race shoes save the weight, the tread stripped down to the bare minimum, but this can leave the carbon exposed to knocks. Rubber tread virtually covers the entirety of the MX331 shoe, protecting the carbon. The design offers improved grip on rocky hike-a-bike sections, avoiding the ice skating effect of carbon on wet rock. The tread is constructed of hard rubber, not plastic, for better grip, although none of the tread is replaceable. Up front are the now, obligatory, thread holes for spikes. Threaded blanks are supplied to avoid the holes filling with mud. The carbon sole comes up high at both the arch and outside of the foot, giving solid support for the foot under hard efforts, with a reinforced weave in the cleat area.

The upper is a double layer of kangaroo leather, tough and breathable. Open mesh sections deliver on breathability, offering a cooler foot, and the double closed sections of leather are in high impact areas, giving the shoe a real robustness. The kangaroo leather itself is tough and more breathable than its synthetic equivalents. All this adds grams but harks back to that characteristic toughness of those early shoes. The tongue is of the same leather, but with a softer lining underneath.
The Boa system needs no introduction, now omnipresent on many cycling shoes. Without the need for the boa lace to wrap around the heel, the dial is well placed on the shoe upper for easy dialing. For an even greater tension over the forefoot, there is the option of threading the laces through additional hooks. A neat little plastic tab between the 2 laces exiting the dial evens up the pull on both laces when loosening them off.
The moldable heel counter is the shoe’s piece de resistance. In terms of general fit, the shoe felt secure with just the boa lacing, but add in a molded heel and the difference is immediately apparent. The molding process is straight forward, all details are included with the shoe, but it is more effective to have a shop do it for you. If doing it DIY, use a thick glove as the carbon will be hot! Once heated to the correct temperature, it’s a matter of using your fingers to shape the heel counter around your heel and then allowing it to cool with foot in-situ. Once done, you will find that the laces no longer have to be dialled down as tightly to maintain a secure fit.

The standard fit MX331 is a narrower fit. Those with a wider foot will need the wide fit option (obviously!). Check out the foot measuring chart on the Lake website to find your size. The range of sizes is comprehensive, with some half sizes and a full range of sizes in a woman’s specific fit, up to a 46.5.
The weight of the MX331 wasn’t an issue and as a consequence they are still going strong, with barely any damage to the carbon sole. It’s that age old trade off between weight and durability. Due to their robustness, I have been happy to use these as the go to shoe for most rides and due to their comfort and spot on fit. The kangaroo upper has taken a beating from a high amount of hike-a-bike, racing and riding, but it has stood up well with no tears in the material, with just a few scrapes evident. These are tough shoes.
The supplied footbeds were immediately comfortable, with no hot spots under the foot arches on any rides. This is a race shoe designed to be effective on the bike and it delivers. Once molded, the heel fits like a glove and feels secure with no amount of heel lift when riding. Power transfer from the carbon sole is race shoe stiff, yet has just enough flex in the toe box for brief hike-a-bike sections. The rubber tread grips well, giving confidence, even on wet surfaces.
A fan of the boa dial, offering an even spread of pressure across the foot as with laces, but without loosening off, it has been pushed to the limit in wet conditions, yet it remains easy to use. The simple plastic tab makes it so much easier to quickly and effectively loosen the laces off. Nice detail.
It may not be super light, but the Mx331 ticks all the boxes, a tough racing shoe with some top features. The underlying features of the MX331 are not dissimilar to their early models, but have the added performance of modern tech. These shoes are a worthwhile investment and will stand up to heavy use whether racing or not.