Shimano Adapter Dura-Ace Di2 for FD-R9150

Synchronized Shift enables more efficient gear changes while riding. This feature offers numerous advantages, such as faster and more precise shifting under all riding conditions, and minimizes stress on the drivetrain. When Synchronized Shift is activated, both the derailleur and front derailleur can be controlled with a single switch. With the fully activated Synchronized Shift function, the front derailleur detects the position of the rear derailleur and automatically shifts to the most efficient gear with the best chain line, so you no longer have to worry about shifting or cross-chaining. With the Semi-Synchronized Shift function activated, you can manually shift the front derailleur, giving you optimal control in selecting the best gear combination for your riding style. The system automatically makes the necessary corrections by shifting to the correct rear gear with the best chain line.