How to Fix a Misaligned Bike Derailleur

Overview

A misaligned derailleur causes poor shifting. This guide covers realigning a bike derailleur.

Step-by-Step Fix

1. Carefully inspect the derailleur hanger (the metal plate connecting the derailleur to the frame) for any bends or damage; it should be perfectly straight and parallel to the wheel. If it looks bent, you'll need a special tool (a derailleur hanger alignment gauge) to straighten it, or visit a bike shop, as a bent hanger is often the root cause of shifting issues.
2. With the derailleur hanger confirmed straight, check if the derailleur body itself is sitting correctly; it should align vertically with the sprockets. If it appears twisted or loose, gently tighten its mounting bolt, ensuring the derailleur doesn't rotate freely.
3. Identify the high (H) and low (L) limit screws on the derailleur, which prevent the chain from going off the smallest and largest cogs respectively. Adjust the H screw so that the upper jockey wheel aligns precisely under the smallest rear cog, and the L screw so the upper jockey wheel aligns exactly under the largest rear cog, ensuring the chain doesn't rub or drop off at either extreme.
4. Now, adjust the cable tension using the barrel adjuster where the cable meets the derailleur, or the inline adjuster if present. Shift into the smallest cog and turn the adjuster clockwise to loosen the cable or anti-clockwise to tighten it, making small quarter-turn adjustments until shifting feels smooth and precise up and down the cassette.
5. Finally, slowly and carefully cycle through all the gears, both up and down, checking for smooth and positive engagement on every single cog. Ensure the chain doesn't hesitate, skip, or make excessive noise, and if it does, make further micro-adjustments to the cable tension or limit screws as needed.

Common Symptoms & Diagnostic Resolutions

Review the common error codes and operating symptoms below to quickly identify the root cause of the fault before ordering replacement parts.

Frequently Asked Questions