Last updated: July 2026
If your bike is clicking, hesitating between gears or refusing to shift smoothly, the cause may be simpler than it first appears. Minor shifting problems are often caused by cable tension, dirt or a slightly misaligned derailleur rather than a major mechanical fault.
This beginner’s guide explains what to check, how to make small adjustments and when to stop and book a professional repair.
What does poor gear adjustment feel like?
Clicking in one gear
The indexing or cable tension may be slightly out, leaving the derailleur between two sprockets.
Slow shift to a larger rear cog
The system may need slightly more cable tension, or the cable may be dirty or damaged.
Slow shift to a smaller rear cog
There may be too much cable tension, cable friction or a derailleur that is not returning freely.
Chain falls off the cassette
A limit screw, derailleur hanger or wheel-position problem may need urgent attention.
Gears shift differently across the cassette
A bent derailleur hanger, worn drivetrain or incompatible component may be preventing accurate indexing.
Chain jumps under pressure
The chain, cassette or chainring may be worn. This is not always an adjustment problem.
Tools you may need
For simple checks and minor adjustments, you may need:
- a bicycle workstand or another secure way to raise the driven wheel
- the correct Allen keys
- a suitable screwdriver for the derailleur limit screws
- chain cleaner, brushes and bicycle drivetrain lubricant
- good lighting
- protective gloves
A derailleur-hanger alignment gauge and chain-wear tool are useful, but these are normally workshop tools rather than essential beginner equipment.
Safety before you begin
- Support the bike securely before turning the pedals.
- Keep fingers, clothing and tools away from the moving chain, sprockets and chainrings.
- Do not adjust gears while riding.
- Switch an electric bike off before working on the drivetrain.
- Remove the e-bike battery if the manufacturer permits and this can be done safely.
- Never use the electric motor to spin the drivetrain while making adjustments.
Understand the three main adjustments
Indexing and cable tension
Indexing aligns each click of the shifter with a sprocket on the cassette. On most cable-operated systems, small indexing corrections are made with a barrel adjuster.
High and low limit screws
The limit screws stop the derailleur travelling too far in either direction. They help prevent the chain falling beyond the smallest or largest sprocket.
They are commonly marked:
- H: controls travel towards the smallest rear sprocket—the highest or hardest rear gear
- L: controls travel towards the largest rear sprocket—the lowest or easiest rear gear
B-tension adjustment
The B-tension screw controls the distance between the rear derailleur’s upper guide pulley and the cassette. The correct gap varies between drivetrains, so follow the component manufacturer’s specification rather than guessing.
How to adjust rear bike gears
Clean and inspect the drivetrain
Remove excessive dirt from the chain, cassette and derailleur pulleys. A dirty or dry drivetrain can create noise and slow shifting that feels like an adjustment problem.
Look for:
- a visibly bent derailleur or hanger
- frayed, corroded or damaged gear cables
- split or sharply bent cable housing
- loose derailleur mounting bolts
- damaged sprocket or chainring teeth
- stiff or damaged chain links
Check the rear wheel position
Make sure the rear wheel is seated correctly in the frame and the axle or quick-release mechanism is secured according to the manufacturer’s instructions.
If the wheel is sitting at an angle or is not fully seated, gear alignment and brake operation can both be affected.
Test every rear gear
Raise the rear wheel and turn the pedals gently by hand. Shift one click at a time across the cassette and observe where the hesitation or noise occurs.
Do not make an adjustment until you know which direction is causing the problem.
Use the barrel adjuster
The barrel adjuster may be located at the rear derailleur, at the shifter or where the cable housing meets the frame.
- If the chain hesitates when moving to a larger rear sprocket, turn the barrel adjuster anticlockwise to add a small amount of cable tension.
- If the chain hesitates when moving to a smaller rear sprocket, turn the barrel adjuster clockwise to reduce cable tension.
Work in quarter-turn steps. Shift through the gears after every adjustment and avoid making several turns at once.
Check the indexing across the cassette
Once one gear shifts correctly, test all the others. The chain should settle onto each sprocket without constant clicking, hesitation or an attempt to move into the neighbouring gear.
If one barrel-adjuster setting cannot produce accurate shifting across the whole cassette, the problem may involve hanger alignment, cable condition, drivetrain wear or incompatible parts.
Check the limit screws only when necessary
Do not use the H and L screws to correct ordinary clicking between gears.
The limit screws may need attention if:
- the chain cannot reach the smallest or largest sprocket
- the derailleur tries to move beyond the cassette
- the chain falls between the cassette and frame
- the chain moves dangerously towards the spokes
When viewed from behind, the upper derailleur pulley should align with the appropriate outer sprocket at each limit. Make very small adjustments and follow the derailleur manufacturer’s instructions.
How to adjust a front derailleur
If your bike has two or three front chainrings, the front derailleur must be positioned and adjusted correctly.
The main factors are:
- derailleur-cage height above the largest chainring
- cage alignment with the chainrings
- inner and outer limit settings
- cable tension
Common front-shifting symptoms include:
- the chain rubbing against the derailleur cage
- slow shifting between chainrings
- the chain falling towards the frame
- the chain overshooting the largest chainring
Front-derailleur adjustment varies considerably between manufacturers and drivetrain designs. Some modern systems also require particular setup blocks, cable-routing positions or trim procedures.
If the derailleur position itself needs changing, consult the correct manufacturer instructions or ask a workshop to adjust it.
Avoid excessive cross-chaining
On bikes with multiple front chainrings, extreme gear combinations can place the chain at a severe angle. Examples include using the largest front chainring with the largest rear sprocket, or the smallest front chainring with the smallest rear sprocket.
This can increase noise and drivetrain wear even when the gears are adjusted correctly. Choose a straighter chain line where possible.
When adjustment will not solve the problem
Persistent poor shifting may be caused by:
Bent derailleur hanger
Even a small bend can make accurate indexing across the cassette impossible.
Worn chain or cassette
A worn drivetrain may jump under pressure even if it shifts normally in a workstand.
Damaged cable or housing
Corrosion, contamination and tight bends can prevent the derailleur returning freely.
Crash damage
A knock on the drivetrain side can damage the derailleur, hanger, cable or frame mounting point.
Incorrectly fitted wheel
A wheel that is not properly seated changes the cassette’s position relative to the derailleur.
Incompatible components
Mismatched shifters, derailleurs, cassettes or chains may not index correctly together.
Special considerations for electric bikes
Most derailleur adjustments on an e-bike follow the same basic principles as on an ordinary bicycle. However, motor assistance can place more load through the chain and sprockets.
- Reduce pedal pressure briefly while changing gear.
- Avoid shifting several gears at once under heavy motor load.
- Inspect and lubricate the chain regularly.
- Check chain wear before it damages the cassette or chainring.
- Have persistent jumping or grinding investigated promptly.
Hub-motor e-bikes usually use conventional derailleur adjustment. Mid-drive e-bikes can apply considerably more force through the drivetrain, making correct technique and maintenance especially important.
Beginner troubleshooting order
- Switch the bike off and support it safely.
- Clean and inspect the drivetrain.
- Check that the rear wheel is fitted correctly.
- Look for derailleur or hanger damage.
- Test every rear gear while turning the pedals gently.
- Use the barrel adjuster in quarter-turn steps.
- Check limit screws only if the derailleur cannot reach—or travels beyond—the outer gears.
- Check for worn parts or cable friction if indexing remains inconsistent.
- Test ride carefully away from traffic.
When should you book a repair?
Professional inspection is recommended if:
- the bike was crashed or knocked over on the drivetrain side
- the derailleur or hanger appears bent
- the chain keeps falling off
- the derailleur is close to the wheel spokes
- the chain jumps when you pedal firmly
- the cable is frayed, corroded or damaged
- shifting remains inconsistent after careful indexing
- you are unsure about the limit-screw settings
Still struggling with your bike gears?
Our Twickenham workshop can inspect gear indexing, cables, chains, cassettes, derailleurs and hanger alignment on compatible bikes and e-bikes.
Final thoughts
Good gear shifting depends on cable tension, correct derailleur alignment and components that are straight, clean and within their wear limits.
Many minor rear-shifting problems can be corrected with a quarter-turn adjustment at the barrel adjuster. The key is to identify the direction of the problem, make one small change and test again.
Avoid turning random screws in the hope that the problem disappears. If careful indexing does not produce consistent shifting across the cassette, investigate alignment, cable condition and drivetrain wear—or arrange a professional inspection.
Frequently Asked Questions
Why is my bike clicking between gears?
The indexing may be slightly out, leaving the derailleur between two sprockets. Dirt, cable friction, wear or a bent hanger can cause similar symptoms.
What does the barrel adjuster do?
It makes small changes to cable tension so each click of the shifter aligns more accurately with a rear sprocket or front chainring.
Which way should I turn the barrel adjuster?
Turn it anticlockwise to increase cable tension if the chain struggles to move to a larger rear sprocket. Turn it clockwise to reduce tension if the chain struggles to move to a smaller sprocket. Use quarter-turn steps.
What do the H and L screws do?
They restrict the derailleur’s outer and inner travel. On a rear derailleur, H controls travel towards the smallest sprocket and L controls travel towards the largest sprocket.
Why do the gears work in a stand but jump while riding?
The chain or cassette may be worn, or the drivetrain may be reacting to load that is not present when the wheel is spinning freely.
Why will my gears not index correctly across the cassette?
A bent derailleur hanger, damaged cable housing, drivetrain wear, wheel-position problem or incompatible component may be preventing consistent alignment.
Can I adjust e-bike gears in the same way?
Generally, yes, if the e-bike uses a conventional cable-operated derailleur. Switch the electrical system off and never use the motor to turn the drivetrain during adjustment.
