Surly Bikes designs and imports bicycles as well as bicycle frames, parts, and accessories, specializing in steel bicycles and frames. Surly is owned by and shares facilities with Quality Bicycle Products (QBP). The company helped establish the Single Speed World Championship (SSWC).
Components made by Surly include the dingle cog, cranksets with separately detachable spiders, a reversible chain tensioner, and fat bike rims. Surly also markets branded lifestyle products.