I have seen custom boot-fitting’s new frontier, and it’s wearing garish socks. OK, so I’m the one wearing garish socks (see photo below), but those gridded, neon stockings really do represent something big. 

Making its North American debut this winter at Gorsuch, the Ertl/Renz boot-fitting system is named for its founders: Sven Renz and his wife, Martina Ertl, a five-time Olympic ski racer from Germany. Ertl/Renz might be better termed a boot-making system, since it results in a pair of boots built from the shell in, practically from scratch. 

Here’s how it works: On went the socks, and up I hopped onto a platform, where a camera captured three-dimensional scans of my feet and lower legs, using the socks’ grid pattern to gauge measurements to the tenth of a millimeter. My left foot, I learned, measures 28.94 centimeters; my right, 28.60.

Those measurements—there were twelve in all, including my instep height and calf circumference, neither of which is any of your business—would be sent to the Ertl/Renz lab in Munich, where master podiatrists use wood and composite materials to create two things: the first are to-the-millimeter reproductions of my feet and lower legs that will be used to make foam-injected liners. The second are “plugs,” the boot-fitting term for replications of the shape of the custom liner with my foot in it, which will allow Ertl/Renz to shape the boot shell to my physical particularities from the knee down. Custom insoles are also made using a pressure scan from my time on the platform.

Off of the platform (but still grooving in the socks), I filled out a questionnaire identifying my skiing ability (expert, thank you very much) and aspirations (ski the toughest terrain I can all day), as well as my height (six-one) and weight (let’s just say 170). Gorsuch Vail’s Billy Schoff and the Aspen store’s Jared Ettlinger then pressed the “shoe me” button, which prompted the computer to suggest my boot’s shell dimensions and flex. The program proposed a flex of 120 (for reference, 150 is for World Cup racers) and 29.0 as my size. But it also allowed my scan to be projected into other shell sizes on the screen, showing exactly how my feet would fare in them. In the end, I opted for a 28.0, the size I’ve skied in for years. (As Ettlinger pointed out, the system, being European, has a slight bias toward comfort, though not one that would detract from performance.) 

Next step: the making of the boot in Munich. Ertl/Renz contracted Lange and Salomon to create shell components with graphite in the plastic (which is why all Ertl/Renz boots are black). This allows the shells to be heated to 350 degrees Fahrenheit—a temperature that would turn most other ski boots into puddles—to mold them to the custom plugs. A shell this customized for the general public really is boot-fitting terra incognita; it’s like the difference between a tailored suit and a bespoke one. And so is the price: a pair of Ertl/Renzes ranges from $1,450 up to $2,750, based on additional bells and whistles, which include remote-controlled heated liners.

Two weeks later, my boots arrived. I put them on and buckled them up. They felt like—well, like they were built by a group of obsessively precise German boot gnomes using magical graphite pixie dust to create something that seems an extension of my body. Hacky Sack, anyone? The sensation of a foam liner—denser, less cushy—was unusual at first, and I had to begin to retrain myself not to buckle the boots too tightly, as I would with my old Nordicas. 

And how do the Ertl/Renzes ski? They are by far the best skiing boots—that is, how well they allow me to turn my skis—that I have ever owned. I’ve been an obsessive boot-tinkerer for years, constantly in search of perfect balance on my skis. I’ve had cants ground into my boots’ soles, and shims placed under my toes to lessen my forward pitch on the skis. To test my balance while skiing, I usually try to make turns on both edges of one ski while skiing only on that ski. I’ve often been able to do it on my left ski, but rarely on my right. The Ertl/Renzes make it possible on both, and with zero adjustment. 

I think a big part of why is the fact that the boots don’t pitch me too far forward on my skis. And their ultra-precise fit gives them great snow feel. I can literally feel terrain variations in the bottoms of my feet. Two friends have independently observed that the boots have made me a better skier. For me, that’s well worth the price.