Keeping your bike’s derailleurs properly adjusted is crucial for smooth, consistent shifting. This guide will teach you everything you need to know about adjusting front and rear derailleurs on your own.
A derailleur is a critical bike component that moves the chain between rear cogs and front chainrings. Over time, derailleurs can become out of alignment due to issues like cable stretch, accidentally hitting the lever, or crash damage. Learning proper derailleur adjustment technique allows you to restore crisp shifting to keep you riding happily on the trails or roads.
Understanding the Derailleur
Derailleurs come in front and rear pairs, working together to give access to a wide range of gears.
What is a Derailleur?
A derailleur is composed of a movable chain guide that uses a system of jockey wheels and tension pulleys to literally derail a chain from one gear to another when the shifter is actuated.
Role of a Derailleur
The rear derailleur positions the chain on the selected rear cog, while the front derailleur shifts between front chainrings. Having multiple chainrings and cogs allows for a wide range of gear ratios.
Types of Bike Derailleurs – Front vs Rear
There are significant differences in adjustment between front and rear units:
- Front: Shifts between 2-3 chainrings
- Rear: Shifts across 8-12 rear cogs
Understanding these differences will help you adjust each derailleur properly.
Components of a Derailleur
Derailleurs have delicate components that need proper positioning to work correctly:
Derailleur Cage
The movable parallelogram chain guide that positions the chain side to side.
Jockey Wheels
Pulleys that guide the chain over cassette cogs.
Tension Pulley
Applies rear derailleur spring tension to take up chain slack.
Guide Pulley
The jockey wheel that guides the chain on and off the selected cog or chainring.
Derailleur Hanger
The rear frame dropout that holds the derailleur in position.
Limit Screws – Low/High
Screws that set how far inboard or outboard the derailleur can shift the chain. Correct limit screw adjustment prevents overshift and chain drop.
When to Adjust the Derailleur
Derailleurs fall out of adjustment over time and use, requiring realignment for proper shifting function.
Shifting Issues
If shifting quality declines – slow, delayed, or inconsistent shifts – a derailleur adjustment is needed.
After a Crash
Crashes can bend parts, requiring derailleur realignment. Always check shifting after any bike crash.
See also: Gear Cycle vs Normal Cycle: Which One is Right for You?
Routine Maintenance
It’s wise to periodically check and tweak derailleur adjustment every few months for optimal drivetrain performance.
Tools Needed for Adjustment
You’ll need a few basic bike tools:
Screwdrivers
For turning limit screws and gear cable anchor bolts.
Hex Keys
For adjustments to cable tension at shifters.
Cable Cutter
To trim and reinstall any frayed shift cables.
Adjusting the Rear Derailleur
Rear derailleur adjustment requires setting limit screws, indexing adjustment, and potentially replacing frayed cables if needed.
Step 1: Set the Low Limit Screw
The low limit screw stops the derailleur cage from shifting past the largest, “lowest” rear cog. If set incorrectly, the chain can derail past the cassette and get stuck.
Step 2: Set the High Limit Screw
The high limit screw prevents overshifting past the smallest cog. Set this screw so the chain does not shift past the smallest cog into the wheel spokes.
Step 3: Adjust the Indexing
Indexing refers to aligning each gear selection with its corresponding cog for clean shifting. Misaligned indexing causes hesitant gear changes and gear slippage.
Step 4: Replace Cables if Needed
Check shift cables for kinks, fraying, broken strands or grittiness. Damage cables greatly impact shifting performance, necessitating replacement.
Adjusting the Front Derailleur
Front derailleur adjustment steps are similar but must also set the fixed chain guide position:
Step 1: Set the Low Limit Screw
Stop inner cage movement so chain cannot overshift past smallest front chainring.
Step 2: Set the High Limit Screw
Prevent outer cage overshift past the largest front chainring.
Step 3: Adjust the Fixed Position
Set fixed guide clearance between cages and each chainring at the halfway shift point for smooth transitions between rings.
Step 4: Replace Cables if Needed
Inspect and replace any damaged front shift cables.
Derailleur Adjustment Best Practices
Follow proper process to ensure excellent results:
Find the Cause of Misalignment
Diagnose the root issue before adjusting – crash damage, stuck cable, worn drivetrain parts, etc can influence adjustments needed.
Adjust in Small Increments
Make minimal position tweaks then check shifting. Over-adjusting limits requires restarting the process.
Check After Each Adjustment
Shift through entire gear range after each screw turn or cable tweak to confirm adjustments help achieve proper shifting function.
Maintaining Proper Derailleur Function
Besides adjustments, regular service prolongs performance:
Keep Components Clean
Mud and grime negatively impacts shifting. Rinse grimy sections with water after muddy rides.
Lubricate the System
Oil the derailleur pulleys and apply grease or lube to shift cable housing. This reduces friction that can inhibit precision.
Inspect Cables Frequently
Replace any cables with broken strands, grimy deposits, or gritty/sticky operation.
Troubleshooting Derailleur Issues
Here are solutions to common shifting problems:
Not Shifting Properly
Re-index and check condition of shift cables. Frayed cables or damaged housing needs replacement.
Clicking Noises
Apply lube to derailleur pulleys and check for stiff chain links that may need replacement.
Chain Slipping
Recheck limit screws, indexing adjustment and inspect worn drivetrain parts like cassettes and chains which may need replacement.
Stiff Lever Feel
Lubricate shift cables and cable housing. Frayed cables increase friction and require replacement.
FAQs on Derailleur Adjustment
How do I know which way to turn the limit screw?
Turn counterclockwise to allow more movement in that direction, clockwise to reduce movement range. Refer to screw markings to identify high vs low screws.
Why does my bike make noise only when pedaling hard?
Stiff chain links as they engage the derailleur pulleys under high torque can create clicking noises. Clean and lubricate the chain or replace stiff links if needed.
What causes ghost shifting?
If gears seem to skip or change on their own, damaged shift cables with high friction levels can prevent the derailleur returning fully after a shift. Cable replacement will rectify ghost shifting issues.
How often should cables and housing be changed?
Most riders should plan to install fresh shift cables and housing at least once yearly to maintain optimal shifting performance. Check cables frequently for fraying that necessitates more frequent replacement.
Can I use soap and water to clean a drivetrain?
Water alone can wash away lubricants, promote corrosion, and force contaminates into bearings. Bike-specific degreasing and lubricating products are engineered to displace grit and moisture safely.
Conclusion
Keeping your derailleurs properly tuned is vital for dependable shifting across every terrain. Follow the steps outlined to confidently adjust front and rear derailleurs. Implement best practices like routine drivetrain cleaning, lubrication, and cable checks to prevent issues before they happen. Your bike will shift like new so you can focus on the ride ahead!
