Dura ace r671 di2 tt shift switch set with di2 technology shifting is easy and precise just a light touch as soft as a mouse click is sufficient for the front or rear derailleur to instantaneously select the correct gear the removal of traditional mechanical cables in favour of electrical wires eliminates poor shifting caused by contaminates corrosion and stretching and also provides effortless gear shifts simply pressing tactile buttons allows effortless and comfortable shifting even when