Decathlon’s own-brand products account for roughly 60% of everything the company sells — including, notably, running shoes. The running aisle in any Decathlon store can have 30+ models across two brands, four categories, and a price range from £25 to £110. For a retailer that positions itself as making sport simple and affordable, the running shoe section is surprisingly hard to navigate. Most people stand there for ten minutes, pick whatever looks good, and buy the wrong shoe. Not catastrophically. No immediate injury. Just a pair that compresses flat in four months instead of eight, or low-grade knee soreness after…