Footwear strobel with bladder having grooved flange and method of manufacturing

A method of manufacturing footwear comprising:

• forming a strobel by welding a first polymeric sheet and a second polymeric sheet to one another to define a peripheral flange having a groove, and to define a plurality of interior welds;
• and
• securing the strobel to an upper along the groove in the peripheral flange of the strobel;
• wherein the strobel includes a polymeric bladder defining an interior cavity and configured to retain a fluid in the interior cavity, the peripheral flange extending around at least a portion of a perimeter of the interior cavity;
• and
• wherein welding the first and second polymeric sheets to one another includes welding a first weld and a second weld spaced apart from one another and extending lengthwise along the peripheral flange, with the groove extending lengthwise along the peripheral flange between the first weld and the second weld.