Quick and smooth front shifting is guaranteed under all circumstances, even when you’re shifting to the large chainring while riding out of the saddle. Due to SHIMANO SYNCHRONIZED SHIFT the front derailleur will shift automatically when the rear derailleur is shifted, allowing both derailleurs to work together efficiently. With SEMI-SYNCHRONIZED SHIFT it’s the other way around, with the rear derailleur shifting automatically when the front derailleur is shifted, obtaining optimal front/rear gear positioning. At the same time, Di2’s auto-trim feature will automatically centre the front derailleur precisely around the chain, avoiding chain rub as you move the chain across the cassette. This is how fast, precise and smooth your shifting can be.