Now in its second generation, Shimano's Ultegra Di2 boasts the same 11-speed shifting as its big brother Dura-Ace.
By eliminating the friction caused by cables and housing, the ST-6870 levers allow lightning quick shifts through 11-speeds. Gear changes are much faster than Shimano's mechanical systems and the shift pads require just 2mm of movement for actuation. Multiple strokes can be made while coasting and the multiple shifts will catch up as soon as pedaling is resumed.
Unlike Shimano's mechanical systems, the brake lever is no longer used for down shifts -- there are two shift pads placed behind the brake lever to control gear changes. The ergonomics of the hoods are similar to the mechanical Ultegra, yet slightly slimmer since they don't need to have room for cables and housing. The brake pivot has been moved closer to the hand for easier reach and better braking power and modulation. Reach is also adjustable for different sized hands. Braking still uses traditional cable and housing (included).
The Ultegra Di2 ST-6870 STI Levers are sold as a pair without electronic wires. 313g/pair.
Note: The ST-6870 Levers are only compatible with Dura-Ace 9070 series Di2 11-speed components or wires.