TT / Aerobar 2-button Shifting Switches
The two-button SW-R671 remote TT/Triathlon shifter allows for shifting when using TT aero bars. It is mounted at the end of the aero bar/extension. It is compatible with all Di2 series, except 7970.
Unlike all other current TT/Triathlon switches, these SW-R671 switches have two buttons each. This means they can be used to shift the front derailleur as well as the rear derailleur.
All other aerobar shifters have only one button each, meaning that those newer shifters will work with Synchronized Shift only.
These switches come with EW-SD50 wires attached to them. The (fixed) length of these wires is 600mm for each of the shift switches, which should be long enough for most TT bikes and aero extensions.