The Shimano Ultegra ST-6870 is the right-side dual control lever from the 6870 Di2 series, designed for road cyclists upgrading to or maintaining electronic 11-speed drivetrains on drop bar bikes. It combines a mechanical brake lever with electronic shift buttons, compatible with Ultegra Di2 6870 components like RD-6870 and FD-6870 derailleurs, using E-Tube wiring for system integration. Riders choose it for reliable electronic shifting across 11-speed cassettes up to 32T (with GS derailleur), customizable via E-Tube software for multi-shift speeds and full-cassette dumps, plus slimmer hoods and textured buttons borrowed from Dura-Ace for better control from hoods or drops. It mounts to standard 23.8-24.2mm handlebar clamps and includes reach adjust for brake lever position. At 152g, it’s lighter than prior 6770 by about 20g per lever, suiting weight-conscious road racers or endurance riders who prioritize crisp shifts over hydraulic braking. Note it requires a Di2 battery and E-Tube setup; pairs with mechanical Ultegra 6800 brakes.