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Test: ‘Heat-Moldable’ Bike Shoes

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On a cold day last month, my planned 10-mile bike ride was halted almost before it began by a broken chain. Under-dressed for walking in the freezing conditions, I decided to run back, and thus I pushed my bicycle a reluctant 2.5 miles back home. This misadventure turned out to be a true test of Shimano’s M240L, a custom-fit mountain bike shoe that you can have “molded” to your foot.

The short story is, I made it home blister-free. Indeed, over the past three months, on rides both short and long (and that one unplanned “hike-a-bike” session), so far I have yet to get so much as a hot-spot in these shoes, which cost $250 a pair.

Shimano M240L custom-fit bike shoe

Shimano touts the M240L shoe as giving “efficiency, fit, stability and durability.” The secret to the custom fit comes from a heat-moldable insole. The “fit” part of it takes about half an hour at a Shimano dealer shop, and it is included in the price of the shoe. Like custom thermal-formable ski boot liners, the bike shoes are warmed in a special “shoe oven.” Then the insole and shoe are vacuum-fit on your foot, snugging the material to match the exact contours from your heels to your toes.

Immediately after my fitting I sensed a snug, performance-ready shoe on my foot. For stiff-sole bike shoes they were super comfortable from the get-go. My men’s size 46 (euro size) shoes weighed in at 16.7 ounces each with the cleat, airy enough for me though not “pro-level” light.

A full-length, carbon-fiber shank sole helps me get power to the pedals efficiently. The shoes’ synthetic uppers are tough but comfortably supple. The unique glittery silver rubber soles have held up in sharp, rocky terrain, and they provide good traction off the bike.

A favorite feature of mine is the “anti-slip heel lining,” which has a gritty fabric knitted with metal fiber. It is also referred to as “shark-skin,” and it does a nice job keeping my foot in place inside the shoe.

Sole view of the M240L

Caveats? Using one of my clipless pedal sets, I experienced some clip-in issues. To remedy, it was necessary to carve some of the sole material away with a knife. But to their credit, these shoes really shined at times when I could not clip-in — the aggressive tread allowed me to stay firmly on the pedals even on gnarly terrain until I could get clipped. (Note: The clip-in problems were with Crank Bros. pedals; using Shimano SPD pedals, no such issues existed.)

If out-of-the-box comfort is a priority, the M240L is a shoe I’d recommend. You need to go in and get “fit,” but the extra step is worth the hassle. And anyone looking for a highly-durable shoe that is light enough to race in would do well to consider these foot-hugging Shimano shoes as well.

—T.C. Worley is a self-proclaimed bike geek.

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