Symptoms
- Shifter doesn't move the chain to the intended gear
- Chain hesitates or delays before shifting
- Grinding noise between gears
- Chain won't reach the smallest or largest cog
Likely causes
- CommonCable tension out of adjustmentCables stretch slightly over time, throwing off indexed shifting.
- CommonDirty or gummed up derailleur and chainBuilt-up grime slows cable and derailleur movement.
- PossibleBent derailleur hangerA hard hit or the bike falling over can bend this small frame piece, throwing off alignment.
- PossibleWorn or frayed shifter cableA fraying cable can bind in its housing and shift poorly.
- PossibleLimit screws misadjustedThese screws set the outer range of derailleur travel and prevent overshifting.
What to do
- Clean the chain, derailleur, and cassette of dirt and old lubricant, then relubricate.
- Shift to the smallest cog and check cable tension; use the barrel adjuster to fine-tune if shifts are slow or hesitant.
- Check the derailleur hanger visually for bending by sighting down it from behind the bike.
- Inspect the shift cable for fraying at the shifter or derailleur end.
- Check the high and low limit screws on the derailleur if the chain won't reach the smallest or largest gear.
- Test shift through the full range after each adjustment, making small changes at a time.
- If shifting stays poor after cable and limit adjustments, a bike shop can check for a bent hanger or worn derailleur.
Tools and parts
- Small screwdriver
- Chain lubricant
- Cleaning rag
Shifter cable and housingSearch: “bicycle derailleur shift cable kit”
When to call a pro
A bike shop can straighten a bent derailleur hanger with a specialized tool or replace it, since hangers are designed to bend before the frame does.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.