How to Install, Adjust, and Maintain the Campagnolo Chorus 12s Rear Derailleur

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in Campagnolo, Rear Derailleur

The Campagnolo Chorus 12s [paid link] rear derailleur is a high-performance component designed for precise shifting on 12-speed road bike drivetrains. Proper installation and maintenance are essential to ensure smooth, accurate shifts and extend the life of the derailleur.

This guide will take you through the full process, including installation, adjustment, maintenance, and troubleshooting. Whether you’re setting up your derailleur for the first time or fine-tuning it for peak performance, this guide has you covered.

Tools Required

  • 5mm Allen wrench [paid link]
  • Torque wrench [paid link] (with Nm settings)
  • Phillips screwdriver
  • Campagnolo 12-speed chain tool
  • Cable cutters
  • Chain lube
  • Degreaser and clean cloth
  • Bike stand [paid link] (optional but recommended)

Understanding the Campagnolo Chorus 12s Rear Derailleur

Before installing the Chorus 12s [paid link] rear derailleur, it’s important to understand its key features:

  • 3D Embrace Technology: Ensures the derailleur stays close to the cassette for better chain retention and improved shifting.
  • Carbon fiber-reinforced construction: Provides a balance of lightweight performance and durability.
  • Optimized for 12-speed cassettes: Works seamlessly with Campagnolo’s 11-29T and 11-34T cassette options.

Step-by-Step Installation Guide

1. Preparing the Bike

Before mounting the derailleur, shift the chain onto the smallest cog and remove any existing derailleur if necessary. Ensure the derailleur hanger is aligned using a hanger alignment tool. A misaligned hanger can cause shifting issues.

2. Mounting the Derailleur

  • Align the B-knuckle of the derailleur with the derailleur hanger.
  • Insert the mounting bolt and tighten it using a 5mm Allen wrench [paid link] to 8-10 Nm torque.
  • Ensure the derailleur moves freely without resistance.

3. Installing the Shift Cable

  • Route the shift cable through the shifter and down to the derailleur.
  • Insert the cable into the clamp bolt and tighten it to 5 Nm while ensuring no slack remains.
  • Trim excess cable and cap the end with a crimp connector.

4. Setting the Limit Screws

Limit screws control the derailleur’s range of motion to prevent overshifting.

  • High-limit screw (H): Adjust to position the upper jockey wheel directly below the smallest cog.
  • Low-limit screw (L): Adjust so the derailleur aligns precisely below the largest cog without overextending.

5. Adjusting the B-Tension Screw

The B-tension screw controls the derailleur’s distance from the cassette.

  • Turn the B-tension screw to maintain a 2-3mm gap between the guide pulley and the largest cog.
  • Too much distance can cause slow shifting; too little can lead to rubbing.

6. Fine-Tuning Indexing

  • Shift through all gears while pedaling.
  • Use the barrel adjuster to fine-tune cable tension until shifting is crisp and accurate.

Maintenance and Cleaning Guide

Proper maintenance ensures your Chorus 12s [paid link] derailleur functions smoothly for years.

1. Cleaning the Derailleur

  • Use a degreaser and a clean cloth to wipe down the derailleur.
  • Remove dirt buildup, especially around jockey wheels.
  • Lubricate pivot points lightly with Teflon-based lubricant.

2. Checking for Wear

  • Inspect the jockey wheels for wear or excess play. Replace them if necessary.
  • Check the cable and housing for fraying or corrosion.
  • Ensure the derailleur hanger is straight, as misalignment can cause shifting issues.

3. Lubricating the Chain

A clean, well-lubricated chain improves shifting and prolongs derailleur life.

  • Apply a high-quality chain lubricant after every 200-300 miles.
  • Wipe off excess oil to prevent dirt accumulation.

Troubleshooting Common Issues

1. Slow or Inconsistent Shifting

  • Check if the cable tension is too loose or too tight.
  • Clean and lubricate the derailleur and chain.
  • Ensure the derailleur hanger is aligned.

2. Chain Skipping Gears

  • Verify the limit screws are properly set.
  • Check for chain wear and replace if it exceeds 0.5% elongation.

3. Excessive Noise While Shifting

  • Inspect jockey wheels for dirt or worn bearings.
  • Adjust B-tension screw to optimize chain gap.

Compatibility with Other Components

The Chorus 12s rear derailleur is designed to work with Campagnolo 12-speed components only. It is not compatible with:

  • Shimano or SRAM 12-speed systems.
  • Older 11-speed Campagnolo drivetrains.

However, it is fully compatible with:

  • Campagnolo 12-speed shifters.
  • Campagnolo 12-speed chains and cassettes (11-29T & 11-34T).

Conclusion

The Campagnolo Chorus 12s rear derailleur is an advanced component that, when installed and maintained correctly, provides flawless shifting performance. By following this guide, you can ensure a smooth setup, precise adjustments, and long-term durability. Regular maintenance and fine-tuning will keep your drivetrain running efficiently for thousands of miles.

For more derailleur setup guides, check out these articles:

Why Your Shimano FD-4700 Might Not Be Set Up Correctly and How to Fix It