Our gear editors are inundated with questions about running shoes. One of the most common: “How does this shoe fit?” That’s because while you may have worn a size 10 in a particular Nike running style, you may be a 9.5 in a New Balance, a 10.5 in an Asics or even have to choose something completely different for your next Nike pair.
Finding the right fit for your perfect pair of running shoes involves dealing with sizing differences between brands. Luckily for runners in the modern age, the sizing differences between shoe brands have largely leveled out. But they still exist.
Brands use lasts, a foot-shaped block around which a shoe is constructed, to create shoes, and these lasts have a major impact on fit. A last is not the only determining factor, however, as the width of the materials used in the running area can affect the fit of the shoes. As brands learn more about fit, each iteration of a popular shoe can also feature a slight change.
Understand the last of a shoe
The lasts fit: In shoe manufacture, the last is the three-dimensional model around which the shoe is “literally built – or tweaked -“, says Simon Bartold, podiatrist with decades of experience in the shoe industry, including in shoe development at Asics and Salomo.
In this sense, the last is similar to a foot, except that most lasts have a completely flat bottom. “The last and last of the shoe are primarily responsible for fit and comfort and determine the volume of the shoe,” says Bartold. “Each shoe manufacturer has their own last, usually just one for major running models, and they’re a well-kept secret because if you get the last right, the shoe is likely to work.”
This fixed shape, which dictates shape and volume, defines everything from toe shape to heel shape, says Caroline Bell, content specialist and shoe fitter at Fleet Feet.
Other factors to fit
While the last is the biggest factor affecting shoe fit, other causes can give a shoe a slightly different feel.
Bell says the type of materials, particularly in the upper, can have an impact. “Materials like knit feel more stretchy than a solid mesh upper, which can alter the fit,” she says. “Even the thickness of the tongue and the lacing pattern can give your foot more or less room. All in all, even the same shoe model could feel very different from year to year if these materials change.”
For example, for 2020 New Balance redesigned the 1080 with a new, more stretchy knit upper that had enough compliance to accommodate additional foot shapes. It felt roomier than the previous version for some runners, but results were mixed in Runner’s World testing. Sure, the upper, tongue, or lacing doesn’t really change the true volume of the shoe—and certainly doesn’t affect the length of the silhouette—but the differences in these elements can still impact the overall fit and feel.
How do individual brands fit together?
One of the biggest questions in the footwear industry revolves around fit. Bartold says that individual brands aren’t particularly known for having a specific type of fit. “It can vary from season to season and certainly from model to model,” he says. “The truth is that sizing is an absolute mess and a headache. Many of the big companies now have entire departments trying to solve the size conundrum. It is estimated that around 70 percent of all shoes are not the right size based on measurement.”
This is often simply proof that the global footwear industry has three equally strong scales of fit. Fit scales in the United States, United Kingdom, and Europe vary slightly, making finding the right size particularly difficult.
Add that anatomy averages can differ from region to region around the world and brands may have a hard time figuring out what works. Bartold says that Salomon, for example, tailored their lasts to a French model, which tends to be narrower than an American counterpart. But that’s not a “cast-iron rule” either. He says that at Salomon, trail shoes tend to be narrower and road shoes tend to be roomier.
“It’s quite common for a particular style from any brand to be true-to-size one season,” he says, “and either bigger or smaller the next.”
Bell says that while brands update models every year or two, no brand runs categorically big or small across the board. “It depends on the model, the latest updates and the materials used,” she says.
Brands often try to tailor a fit to the specific end-use activity. With this philosophy, shoes from the same brand can feel and fit differently. “For example, the Nike Vaporfly line offers a more snug fit than the Pegasus, which is generally true to size,” says Bell. “The Nike Vaporfly is designed for racing, so it offers a performance fit compared to the Pegasus, which is designed for everyday training.”
Even if a brand has made a name for itself with a particular fit, that can change with the release of a new model. Bell says Hoka was once known for feeling big and roomy, but the brand’s sizing has changed dramatically, and while their shoes may still be able to welcome big feet, they now fit more true to size than they used to .
Kris Hartner, owner of Naperville Running Company in Illinois, says it used to be common for brands to vary wildly in size. Many brands now even offer different widths to accommodate a larger number of foot sizes. “I think the lasts are more consistent,” he says. “I think brands have really dialed in and know which shoes fit and which shoes are selling really well.”
Find a better fit with a better last
We are already seeing a shift towards anatomically shaped lasts. “Obviously, if the shoe is to fit better, the last should be shaped more like a human foot,” says Bartold. “A few companies are doing this now, but only a few. It’s also likely that, particularly as 3D printing becomes more viable, companies will have many lasts instead of just one, allowing shoe recommendations to be more finely tuned for specific foot types.”
Find the right fit
Bartold has clear advice on getting the fit right: “Make an appointment with someone who knows about fitting properly,” he says.
New scanners such as volumetal at running stores can help determine fit, but only if used by someone knowledgeable about shoe fitting. According to Hartner, it makes sense to have an expert examine the mechanics of a runner in conjunction with a tool like volume valley.
The main mistake, according to experts, is that people wear shoes that are too small for walking. Hartner says statistics show that 80 percent of people wear their shoes too small, and Bell says most people don’t understand that they need about a half size larger in a running shoe than they do in a casual shoe.
Running and walking can cause feet to swell. Make sure you have enough space at each step. “You should be a half size to full size from the top of your longest toe across the toe box of the shoe while standing,” says Bell, “and make sure your heel is nice and snug in the shoe.”
“Room in the toe is what you want so it fits properly for active use,” says Hartner. “There’s a notion that you want your forefoot so it doesn’t slide around, but as long as it fits properly in the midfoot, you want room in the toe box.”
Length is just one of the important factors to consider. “Foot width and volume are important, as is arch height, foot and ankle movement when walking or running,” says Bell. “The best thing you can do is get fit from an expert at your local running store.”
Tim Newcomb is a journalist based in the Pacific Northwest. He covers stadiums, sneakers, gear, infrastructure and more for a variety of publications including Popular Mechanics. His favorite interviews included sit-downs with Roger Federer in Switzerland, Kobe Bryant in Los Angeles, and Tinker Hatfield in Portland.
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