A confession: We've always loved Shimano's front derailleurs. They've always worked flawlessly and quietly. And then we rode Di2 bikes. The precision of the Di2 front derailleurs cannot be overstated. They work so phenomenally well, so precisely, and so quietly that we often forget they're there. They auto trim, eliminating chain rub, and they adjust themselves when they're out of alignment. It's among our favorite components, and the Ultegra 6870 is a fortunate beneficiary of this technology and design.