Nearly 300 small sports equipment and outdoor wear shops. You can find skis, bikes, clothes and fishing gear here. It is quite chaotic, so be sure to take your time and check out all 3 levels to find what you're looking for. The first floor is mostly given to fishing gear. For camping and hiking gear go to the second, and the third is mostly for clothes - sports, hiking, skiing and just generally outdoors. You can winter shoes here as well.
Map of the center: http://www.extreme-shop.ru/plan.htm
How to get there: http://www.extreme-shop.ru/location.htm
To make shopping in Moscow easier for you, start a proper individual course of Russian today:https://www.moscowliving.org/post/russian-language-for-expats
Location: 63b Smolnaya Ulitsa, near Rechnoy Vokzal metro station