Installation Guide: GRX FD-RX815 / Ultegra FD-R8050 / DURA-ACE FD-R9150 Di2 Front Derailleur

Updated September 11, 2023 by BetterShifting Terry

Installing the GRX FD-RX815, FD-R8050 and FD-R9150 front derailleurs is not hard, but Shimano recommend you do it in two stages. First you attach the front derailleur and the electric wire, then install the Crankset and make the final height adjustments to set up the front derailleur correctly. The tools needed for installation are:

Attach the derailleur to the frame

The current generation FD-RX815, FD-R8050 and FD-R9150 front derailleurs are available in braze-on version only. This doesn’t mean that you cannot use it if your frame does not have a braze-on mount, but you’d need the clamp-on adapter. Follow the steps corresponding to your mounting option.

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.

FD 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, I 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 clamp band. 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.

FD clamp adapter

Install the Electric Wire

Now that the derailleur is attached to the frame, install the Electric Wire. If you haven’t run the wire through the frame yet, now is the time. Ideally you do this before installing the Crankset, allowing for easy access to the front derailleur.

These front derailleurs both come with a wire cover and we recommend you use it. Install the electric wire to the plug cover, and then push the wire and plug cover into the port of the derailleur.

You will need to use enough force and push until you feel it click into place. If you do not feel or hear it click, the wire is not attached properly and will come loose.

FD attach wire

There are two holes in the wire cover, allowing you to use the Plug Installation Tool TL-EW02 to help push the connector into place. The tool can also be used on the wire plug itself.

Set the front 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.

Set FD height

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.

Note: if the derailleur appears to be too close to the frame, screw the high limit screw in a bit more to allow the derailleur to move further from the frame.

FD set correct angle

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.

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.

FD support bolt

Almost done!

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/high limits.

This can only be done once all components have been installed. Read about setting the Top Adjustment bolt on this page.

BetterShifting Terry

About the Author - BetterShifting Terry

I enjoy playing with bike tech - both bike building and wheel building, bike maintenance and of course, Di2. Besides writing content and working on the technical side of BetterShifting, I also work as a Software Developer in The Netherlands. Read more on the About this site page.

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