How to Install, Adjust, and Maintain the FD-6870 Front Derailleur

Posted on
in Di2, Front Derailleur, Ultegra

The Shimano FD-6870 [paid link] front derailleur is an essential component of the Ultegra Di2 electronic shifting system. It offers precise and reliable shifting, making it a top choice for road cyclists. However, proper installation, adjustment, and maintenance are crucial to ensure optimal performance.

This guide will cover everything you need to know about the FD-6870 [paid link], including step-by-step installation, fine-tuning adjustments, and troubleshooting common issues. Whether you’re setting up a new drivetrain or maintaining an existing one, this article will help you keep your shifting smooth and responsive.

Tools Required

To install and adjust the Shimano FD-6870 [paid link] front derailleur, you’ll need:

  • 5mm Allen wrench [paid link]
  • Torque wrench [paid link]
  • Phillips screwdriver
  • Shimano Di2 E-Tube Project software (for electronic adjustments)
  • Chain checker tool
  • Isopropyl alcohol and clean cloth (for cleaning surfaces)

Step-by-Step Installation of the FD-6870 Front Derailleur

1. Preparing the Frame and Mounting Surface

Before installing the derailleur, ensure that the mounting area on the frame is clean and free of debris. Use isopropyl alcohol to wipe down the surface.

2. Attaching the Front Derailleur

  • If using a braze-on mount, attach the FD-6870 directly to the frame’s derailleur hanger.
  • If using a clamp-style mount, choose the appropriate clamp size and secure it to the seat tube.
  • Align the derailleur so that the outer plate is parallel to the chainrings.

3. Setting the Correct Height and Angle

  • The derailleur cage should be 1-3mm above the largest chainring.
  • Adjust the angle so that the outer plate runs parallel to the chainring.
  • Tighten the mounting bolt to 5-7 Nm using a torque wrench [paid link].

4. Connecting the Di2 Electronic Wires

  • Plug the Di2 wire into the derailleur’s connection port until you hear a click.
  • Route the wire neatly along the frame, securing it with cable guides if necessary.

5. Checking Chainline and Clearance

  • Rotate the cranks to check for any interference between the derailleur and the chain.
  • Ensure the derailleur does not contact the frame or chainrings when shifting.

Adjusting the FD-6870 Front Derailleur for Optimal Shifting

1. Basic Di2 Front Derailleur Adjustments

The FD-6870 uses electronic micro-adjustments to fine-tune shifting performance. To enter adjustment mode:

  • Hold down the junction box button for about 5 seconds until the LED turns solid red.
  • Shift into the small chainring and largest rear cog before making adjustments.

2. High and Low Limit Screw Adjustments

  • The low limit screw controls the inward movement of the derailleur.
  • The high limit screw controls the outward movement.

Adjust these screws while in adjustment mode to fine-tune cage positioning:

  • Shift into the small chainring and largest rear cog, then adjust the low limit screw so there is 0.5-1mm clearance between the chain and the inner derailleur plate.
  • Shift into the large chainring and smallest rear cog, then adjust the high limit screw for the same 0.5-1mm clearance between the chain and outer derailleur plate.

3. Performing an Auto Trim Check

Shimano Di2 front derailleurs have automatic trim adjustment to prevent chain rub.

  • Shift through the gears while pedaling and ensure that the derailleur trims itself correctly.
  • If the trim does not engage properly, reconnect the derailleur to the E-Tube Project software and check for firmware updates.

4. Fine-Tuning with E-Tube Software

  • Connect the bike to Shimano E-Tube Project via a PC or tablet.
  • Use the “Front Derailleur Adjustment” feature to make precise micro-adjustments.
  • Save the settings and test shifting under load.

Maintaining the FD-6870 Front Derailleur

1. Regular Cleaning and Inspection

  • Wipe down the derailleur with a clean cloth after every ride.
  • Check for dirt buildup around the pivots and cage.
  • Use mild degreaser to clean the derailleur if shifting feels sluggish.

2. Checking for Firmware Updates

  • Periodically connect the Di2 system to the E-Tube Project software to check for updates.
  • Keeping firmware up to date ensures optimal shifting performance and bug fixes.

3. Battery and Wiring Inspection

  • Ensure the Di2 battery is fully charged before long rides.
  • Check for loose or damaged wiring, as this can cause intermittent shifting issues.
  • If shifting problems persist, perform a connection check using the E-Tube software.

4. Lubrication for Smooth Performance

  • Apply light oil to the pivot points every few months to maintain smooth movement.
  • Avoid heavy grease, as it can attract dirt and cause buildup.

Troubleshooting Common FD-6870 Issues

1. Front Derailleur Not Shifting

  • Ensure the Di2 battery is charged.
  • Check the wiring connections for loose or damaged plugs.
  • Reset the system using the junction box button and try again.

2. Slow or Inconsistent Shifting

  • Check for dirt buildup on the derailleur cage and clean it.
  • Ensure the limit screws are set correctly.
  • Update the firmware through E-Tube Project.

3. Chain Rubbing on the Derailleur

  • Check for proper height and alignment of the derailleur cage.
  • Enter adjustment mode and fine-tune the derailleur’s position.

Conclusion

The Shimano FD-6870 front derailleur is a high-performance electronic shifting component that requires proper installation, precise adjustments, and regular maintenance to function at its best. By following this guide, you can ensure smooth and reliable shifting for your road bike.