If you're looking for a high-quality, precision-shifting, light front derailleur, you've found it in Shimano's Ultegra. It's made of cold-forged aluminum with their wide-pivot design that stops flex for smooth, fast and exact shifts, even under load. And this fine derailleur is built tough for reliability and durability, too.
Capacity is calculated by subtracting your smallest chainring's tooth count from the largest chainring's tooth count. Example: 46/34/24 chainrings: 46 - 24 = 22-tooth capacity.