Shimano Ultegra ST-6870 Dealer's Manual page 41

CONNECTION OF THE ELECTRIC WIRES
Connection of the Junction (B)
Connect the electric wires to the front derailleur, the rear derailleur and the battery mount.
2
Provisionally secure the electric wire
along the frame with tape, and then
connect it to junction (B).
3
To be continued on next page
Using the wider end of the special tool TL-EW02,
(F)
attach the electric cable on the cable holder
(G)
(I)
(H)
41
(F)
Front derailleur
(G)
Rear derailleur
(H)
Battery mount
(I)
TL-EW02
FD-6870 has a cable holder on the back side.
After connection, attach the cable as shown in
the illustration.
If the electric wire is difficult to attach,
remove the rear wheel.
CAUTION
When routing the electric wire to the rear
derailleur, be sure to install it to the bottom
of the chainstay to avoid any interference
between the cable and the chain.