The removal of traditional mechanical cables in favour of electrical wires not only eliminates poor shifting caused by contaminates corrosion and stretching but also provides effortless gear shifts the shimano 6770 ultegra di2 drop handlebar cable for stis non flightdeck cable set is required to connect the shifters to the included battery indicator junction box controller ultegra di2 also requires ew sd50 cables from the battery indicator junction box to the rear mech front mech battery