FSA OS-140 Aluminum Road Stem FSA OS-140 Aluminum Road Stem features: 3-D forged then CNC machined from AL6061-T6 Carbon fiber composite 4-bolt front clamp 31.8mm handlebar clamp only 35mm fork clamp stack height 175 grams. Posted in Bicycle Parts, Bicycle Stems, Cycling, Outdoor Recreation, Sporting Goods