While you may think that front derailleurs haven't changed since the days of down-tube shifters (and we'll admit that we've been among the skeptical), Shimano's 6700 Ultegra front changer is indeed different from the derailleur it's replacing, the 6600, and it is different from the Dura-Ace 7900. This particular Ultegra FD-6700-G Front Derailleur has a smoky grey anodized finish that sets it apart from the standard 6700 version. This color is a perfect match with the rest of the electronic Ultegra Di2 group. Compared to the 6600, this shape of this unit has been tweaked to minimize the need for trimming the front derailleur, and the spring is lighter for less push necessary at the lever. The links have been widened to make the shifter torsionally stiffer. All in all, the shifting will feel smoother, lighter, and more precise. It is different from 7900 in that the cage is wider and designed to work with a front STI shifter that still has an intermediate "trim" shift -- Dura-Ace doesn't have this feature anymore. Shimano says this front derailleur will work with older 6600 shifters, but considers it 'B' compatible -- it works, but not perfectly. The Ultegra FD-6700-G Front Derailleur is designed for compact (110mm bolt circle diameter) and standard (130mm bcd) double cranksets. There are three different versions -- braze-on, 34.9mm clamp and 31.8/28.6mm clamp (which comes with a shim to reduce the diameter from the larger size to the smaller). It can handle a big/small ring differential of up to 16 teeth (think 34/50 chainrings).