How to Adjust a Rear Derailleur – Limit Screws & Indexing

How to Adjust a Rear Derailleur: Step-by-Step Tutorial

1. Introduction to Rear Derailleur Adjustment:

   • The rear derailleur is the mechanism responsible for shifting the chain at the rear cogs of your bike.
   • It is connected to the shifter by a cable that passes through housing, allowing for small incremental shifts with each click.

2. Understanding Limit Screws:

   • Derailleurs are equipped with limit screws that prevent the derailleur from moving too far inward or outward to avoid chain interference with the spokes or frame.
   • Limit screws can be adjusted to fine-tune the derailleur's movement range.

3. Initial Setup:

   • Shift the front derailleur to the largest chainring and the rear derailleur to the smallest cog to ensure the shifter is fully actuated outward.

4. Adjusting the H Limit Screw:

   • If the rear derailleur does not shift to the smallest cog, turn the H limit screw counterclockwise a few turns.
   • Pedal to test the shift and adjust the H limit screw as needed until the derailleur shifts smoothly to the smallest cog.

5. Fine-Tuning the Limit Screws:

   • Adjust the limit screws gradually to eliminate excessive noise while ensuring smooth shifting.
   • Tighten the screws for a tighter setting and loosen them if the noise persists until the derailleur operates quietly.

6. Indexing Adjustment:

   • Indexing aligns the guide pulley with the cogs to ensure each shift corresponds accurately with each cog.
   • Use the barrel adjuster to make incremental adjustments for precise indexing.

7. Fine-Tuning the Indexing:

   • Shift through each rear cog one at a time, adjusting the barrel adjuster as needed to eliminate excessive noise and ensure smooth shifting in every gear.

8. Setting the L Limit Screw:

   • Once indexing is properly set, adjust the L limit screw to prevent the chain from overshifting into the spokes.
   • Gradually tighten the L screw until the derailleur shifts smoothly to the largest cog without excessive noise.

9. Adjusting the B Screw:

   • Check the spacing between the guide pulley and the cogs using the B screw, which controls the body angle of the derailleur.
   • Maintain a gap of 5-6 millimeters between the pulley and the cogs by adjusting the B screw accordingly.

10. Final Checks and Test Ride:

• Test ride the bike to ensure smooth shifting under normal riding conditions.
• Make further adjustments as needed based on any symptoms of slow shifting or excessive noise.

11. Advanced Troubleshooting:

• If issues persist, refer to advanced troubleshooting techniques or seek professional assistance for further adjustments.

12. Conclusion:

• Once adjustments are complete, your rear derailleur should be properly tuned for optimal performance.
• Regularly check and maintain your derailleur to ensure smooth and reliable shifting on your bike.

By following these step-by-step instructions, you can effectively adjust the rear derailleur of your bike for improved shifting performance.