The new wireless Di2 platform ensures fast and smooth shifting at the front derailleur. Additionally, it offers a choice between manual shifting and synchronized shifting assistance modes – Semi-Synchro or Full-Synchro – which feel like having your own personal assistant! In Semi-Synchro mode, the rear derailleur automatically adjusts to avoid large jumps in gear ratios, allowing you to maintain your cadence and rhythm. In Full-Synchro mode, the rear derailleur and front derailleur work harmoniously together, ensuring that you always have the right gear engaged without having to think about it. Seamless communication with the rear derailleur combined with programmed chain management minimizes the risk of chain drop. The maximum number of teeth is 50-52. It’s entirely up to you how often you want to think about the gear ratio!.