Installation of the previous generation Di2 front derailleurs FD-6870 and FD-9070 is a relatively straightforward affair. These front derailleurs have both a top and low limit screw, making installation simple and quick.
Attach the derailleur to the frame
These derailleurs are both meant to be attached using a braze-on mount, but a band adapter is available for frames without such mount.
When there is a mounting boss on the frame
Use your size 5 hex wrench to loosely screw in the mounting bolt and attach the derailleur to the frame. Do not tighten it fully yet.
These derailleurs have a tiny bolt that goes through the derailleur and comes out the back. You’ll later tighten this bolt to sit flush against the frame, giving the derailleur something to push against when shifting.
Now check where the derailleur’s support bolt hits the frame, and stick the backup plate on the frame by peeling off the liner on the back. The backup plate is the small metal plate you got with the front derailleur - it’s there to prevent damage to the frame itself.
Note that if the support bolt touches the frame’s mounting boss itself, you may not need the backup plate. I haven’t used this plate on my Cinelli, for example.
The support bolt should touch the side of the backup plate without the tape. Tighten the bolt until it touches the backup plate.
When there is no mounting boss on the frame
If the frame you’re using does not have a mounting boss you will need a Front-derailleur band adapter. While you can probably get away with using any band adapter, we recommend using the one Shimano make, the SM-AD91 band adapter.
Install the band adapter to the front derailleur using a size 5 hex wrench and the provided bolt. You do not have to install the backup plate, since you'll tighten the support bolt to sit flush against the band adapter. It won't damage your expensive frame.
Now tighten the derailleur’s support bolt using a size 2 hex wrench until it only just touches the backup plate.
Remove the clamp bolt from the clamp band, attach the band to your frame and insert and tighten the clamp bolt. Do not tighten it fully yet, as we haven’t checked the height of the front derailleur yet.
Install the electric wire
Now let’s install the EW-SD50 electric wire. This is easier to do when the crankset has not been installed yet, because you’ll have easy access to the front derailleur area.
If you haven’t run the electric wire through the frame yet, do so now. In order to plug the wire into the socket properly we recommend you use the Shimano Cable Plug tool TL-EW02. You should feel it snap into place. If it doesn’t, the wire is not installed correctly and will most likely come loose.
The FD-6870 and FD-9070 both have a cable holder on the back which you can use to tidy up your cable routing. Whether or not you’ll use this cable holder will depend on where the electric wire exists the frame. If you do use it, the TL-EW02 tool is very helpful pushing the electric wire into place.
Set the derailleur height and angle
Make sure the crankset is installed so that you can secure the front derailleur to the frame at the right height and angle. First we’ll adjust the derailleur height.
Loosen the mounting bolt and move the front derailleur vertically until there is about 1-3 mm of clearance between the chain guide outer plate and the tip of the teeth of the largest chainring.
To set the angle of the Front Derailleur, rotate it so that the flat surface of the chain guide outer plate is directly above the largest chainring and the rear edge of the chain guide is inwards by 0.5 to 1 mm compared to the front edge.
Now let’s straighten up the Front Derailleur so that the chain guide outer plates are in line with the chainring.
Use a size 2 hex wrench to adjust the support bolt and make sure that the flat portion of the chain guide outer plate is aligned with the surface of the largest chainring.
If the support bolt does not touch the backup plate, move the backup plate so that it does.
That concludes the installation of your Front Derailleur. It should now be properly attached to your frame. The only thing that’s left to do is set the Top Adjustment bolt and the low limit.
This can only be done once all components have been installed. Read about setting the Top Adjustment bolt on this page.