How to Adjust Bike Gears
Last updated: 7 September 2026
Adjust the limit screws, cable tension, and index the gears for smooth shifting across all gears.
Overview
Smooth gear shifting makes cycling more enjoyable. This guide covers adjusting derailleurs for precise gear changes.
Step-by-Step Fix
Before beginning any repair, ensure you have isolated power or water supplies. Clear your workspace, gather standard hand tools, and wear appropriate personal protective equipment (PPE).
- Shift to the smallest chainring and smallest cog. This position provides the least cable tension and makes setting up the limit screws easier and more accurate.
- Check the derailleur alignment - it should be parallel to the cogs. If the derailleur is twisted or bent, it will not shift properly. Use a derailleur hanger alignment gauge to check the hanger is straight.
- Adjust the high limit screw (marked H) to prevent chain over-shifting. Turn the screw until the guide pulley aligns directly under the smallest cog, with just a hairs width of clearance.
- Adjust the low limit screw (marked L) to prevent the chain from dropping into the spokes. Shift to the largest sprocket and adjust the L screw so the chain runs smoothly with no rubbing noise.
- Use the barrel adjuster to fine-tune cable tension. Turn it anti-clockwise to increase tension (moves the chain to larger sprockets) and clockwise to decrease tension. Make small quarter-turn adjustments.
- Test shifting through all gears - it should be smooth and quiet. Shift up and down the cassette and listen for any hesitation or grinding. If shifting is poor, make further micro-adjustments to the cable tension.
- If shifting is still rough, check the derailleur hanger for alignment. A bent hanger prevents smooth shifting even with perfect cable tension. If bent, carefully straighten it or replace it.
- Check the B-tension screw to set the correct gap between the derailleur guide pulley and the largest cassette sprocket. Adjust so the pulley sits 5-8mm from the sprocket teeth.
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.
| Symptom / Code | Likely Root Cause | Recommended Resolution |
|---|---|---|
| Chain skips under load | Worn chain or cassette | Replace the chain and cassette if worn. Use a chain checker tool to measure wear - replace if it reads 0.75% or more. |
| Gears will not shift to largest cog | Limit screw too tight | Loosen the low limit screw slightly. Turn the L screw anti-clockwise a quarter turn at a time until the chain shifts to the largest cog. |
| Shifting is slow or hesitant | Incorrect cable tension or sticky cable | Add tension via the barrel adjuster in quarter-turn increments. If that does not help, replace the inner cable and outer housing as they can be dirty or corroded inside. |
| Chain overshoots the largest sprocket | Low limit screw too loose | Turn the L screw clockwise half a turn at a time until the derailleur stops at the correct position without grinding the spokes. |
Frequently Asked Questions
How often should I lubricate the chain?
Every 100-200 miles, or after riding in wet conditions. A well-lubricated chain shifts more smoothly and lasts longer. Use wet lube for wet conditions and dry lube for dry, dusty conditions.
What causes slow gear shifting?
Dirty cables, worn chain, or incorrect cable tension. Also check that the derailleur hanger is not bent and that the derailleur pivots are clean and lubricated.
Can I adjust bike gears myself?
Yes, with a 4mm and 5mm Allen key, a small screwdriver, and some patience. The process is manageable for most home mechanics and regular adjustments keep shifting precise.
What causes ghost shifting (shifting on its own)?
Ghost shifting is usually caused by a bent derailleur hanger, worn cassette or chain, or too much cable tension. Check the hanger alignment first, then inspect the drivetrain for wear.