SHIMANO ULTEGRA DI2 R8150 2x12V Braze-on Front Derailleur

From the new Groupesets electric Ultegra 8050, the SHIMANO Ultegra Di2 8150 2x12V soldered front derailleur has been designed to offer a wider range of gears, without compromising shifting performance, while being as quiet as it is aerodynamic.
 

Fast, fluid shifting Chainrings is guaranteed in all conditions, even when you're shifting on the big Chainring dancer.

Shimano's Synchronized Shift technology synchronizes front shifting with any rear shifting, allowing both derailleurs to work together efficiently.
With Semi-Synchronized Shift technology, it's the other way around: rear shifting is synchronized with any front shifting, thus maintaining an optimal gear ratio.

At the same time, the Di2's auto-trim function will automatically center the front derailleur precisely around the chain, avoiding any chain friction as the chain moves through the Cassette. That's how fast, precise and smooth your shifting can be.