Testing the performance of "HOTRONIC" heat socks, the racing gear used by top athletes

Electrically heated gear has been steadily gaining popularity in the snow sports industry in recent years. This time, our editorial staff put the heated socks from HOTRONIC, a company that partners with national teams from the United States, Austria, and other countries, to the test. We tested their performance in a real snowy mountain environment during the strongest cold wave that has been described as a "once-in-a-decade" cold snap

What is HOTRONIC?

HOTRONIC is a brand developed by the WINTERSTEIGER Group, known for its world-leading automated tuning machine, "Jupiter X."
With the goal of "longer and warmer," the brand employs a team of expert technicians who also conduct boot fitting workshops. Using innovative analytical methods, they develop products that support athletes' activities from the ground up, meeting the individual needs of each athlete.

This technology is used at the forefront of competitive sports, providing custom insoles to athletes in various sports, including alpine skiing for Austria, Germany, and the United States, as well as snowboarding, moguls, ski jumping, and cross-country skiing. Furthermore, it is supported
by a wide range of people, from mountaineers and photographers to athletes in motorsports, soccer, volleyball, and even equestrian sports, as well as general users who want to live an active life.

In Japan, top athletes who compete for results, such as ski crosser Ryu Sugai, who will compete in the Milan-Cortina 2026 Olympics, and FWT competitor Koga Hoshino, also use these socks. Designed for skiers who strive for "faster," these socks eliminate unnecessary tension and cold through warmth, maximizing concentration and reaction speed.
Positioned as a "race gear" item, just like skis and boots, these socks are more than just a cold-weather item. They are equipment for winning, for serious skiers who want to "shave off a tenth of a second" or "precisely carve the line they envision."

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Products developed by the brand

In addition to the heated socks we tried out this time, they also offer insoles and liners, but products equipped with a "heating system" specifically designed for use in cold environments include heated insoles, heated gloves, and heated bags. They also have a small dryer for boots and gloves, and are thoroughly pursuing warmth, comfort, and convenience

About Heat Socks

The "XLP S" series of heated socks comes in three types to choose from depending on your needs and preferred fit: "Comfort" prioritizes comfort, "Thin" balances thinness and warmth so it doesn't take up too much space inside your boots, and "Race" is designed for racing, offering a thin yet warm and comfortable so you can accurately feel the snow surface

There are two heating methods: "Surround," which covers the entire toe area, and "Classic," which efficiently warms the area around the bottom of the toes and the ball of the foot. Furthermore, there are two battery capacities: "XLP 1S," which can be used for approximately 8 to 10 hours at the lowest temperature setting, and "XLP 2S," which can operate for approximately 16 to 18.5 hours under the same conditions

Review of the race model " HEAT SOCKS SURROUND RACE "

The model we tested this time was the "HEAT SOCKS SURROUND RACE," the only one in this series available in Japan (distributed by Kleb Sports). It's a slim-designed model that prioritizes performance, and its main features are as follows.
*Battery set sold separately

The test environments were two different conditions: free skiing on the slopes (mid-January/Nomugi Toge Ski Resort/clear skies/temperature around -5°C), and sitting outdoors all day working at an event reception desk (early February/Hoshino Resorts Nekoma Mountain/light snow/temperature -10 to -5°C). In the former, we focused on the feel and operability while skiing, and in the latter on warmth and comfort when worn for long periods of time, and we will report frankly on the advantages and disadvantages we felt in each situation

Before use, first charge it. Remove the red cover from the battery and connect the USB-C charging cable with the snap connector. Charging takes approximately 5 to 7 hours. If you prepare it the night before, you can finish charging it while you sleep

Free skating test

The next morning, I put them on first. The size is M. The description says the compression is "slightly soft," but in reality it's tighter than I expected, and for an editor with slightly muscular calves, it was quite a challenge to get them on. I felt that they were designed for Western users with slender calves below the knee. However, once I put them on, there was no discomfort, and the fit was the same as regular compression socks. In fact, the instep is soft, smooth to the touch, and feels cushioned

When you touch the heating wire, it feels a gentle, gentle warmth. This is a much safer option than hand warmers, which can pose a risk of low-temperature burns if you touch them for long periods of time, and can heat unevenly if the contents are unevenly distributed

Temperature adjustment is done using the dedicated app "HOTRONIC Heat App" ( Android / iOS versions ), which also provides access to the user manual , but connecting is surprisingly easy. Although the display is in English, if you're familiar with pairing Bluetooth devices, you won't have any trouble. Simply press the buttons on the app and the device itself to connect the left and right sides, select your preferred temperature from four levels, and you're ready to go.

The battery case is made of flexible silicone and is designed to curve slightly to fit the shape of your legs, and it's not particularly heavy compared to other ski gear

At first, I felt a slight discomfort on the soles of my feet, but once I started skiing, I quickly forgot about it. I tried wearing only one foot for a day, and the difference was clear. While the unheated foot was distracted by the cold, the one with the shoes on allowed electricity to circulate, allowing me to concentrate on skiing without any unnecessary distractions

Quiescent (standby) test

These high-end socks were developed for extreme environments, primarily racing, so we tried them out in an everyday environment, ideal for standby time. The conclusion is that they are warm. If we had to point out any drawbacks, they would be the effort of putting them on, the price, and the need to be a little careful when washing them by hand

The battery capacity is sufficient for a comfortable "day." The weight and size of the device are not as noticeable as I imagined. Compared to wearing gritty shoe warmers and constantly feeling like you're stepping on something, the comfort is clear. The fact that it's warm but doesn't get stuffy is also more comfortable than I imagined. The material contains 40% merino wool, which provides high levels of heat retention and moisture absorption/release

This is unmistakable racing gear, made with the same cutting-edge technology as the skis and boots, in order to shave off every tenth of a second. The results showed its true capabilities. If you're interested, be sure to give it a try

Information

BOOTDOC-HOTRONIC

Official website:https://www.bootdoc-hotronic.com/en_us/index.html
Official social media:Instagram|Facebook|X

Clev Co., Ltd. Clev Sports

〒949-6102 39-8 Kandachi, Yuzawa-machi, Minamiuonuma-gun, Niigata Prefecture
Official website:https://www.xraeb.co.jp/xraebsport
SNS:Instagram|Facebook