Shimano Ultegra Clamp-On Front Derailleur
Details
If you're looking for a quick-shifting, super-light front derailleur, you've found it in Shimano's Ultegra. The wide pivot-link design suppresses flex for light, fast and precise shifts, even under load. And this fine derailleur is built tough for reliability and durability, too.
Also available in Silver (image unavailable from manufacturer).
Your seat-tube diameter determines the needed derailleur clamp size.
Capacity is calculated by subtracting your smallest chainring's tooth count from the largest chainring's tooth count. Example: 53/39 chainrings: 53 - 39 = 14-tooth capacity.