Derailleurs & Drivetrain Maintenance

Derailleurs & Drivetrain Maintenance

Smooth, accurate shifting is one of the best feelings on a road bike. It’s what lets you hit the right gear mid-climb, accelerate efficiently, and ride without distractions.

Over time cables can stretch, housing collects grime, and derailleur alignment can slip, which leads to sluggish shifting, chain rub, or annoying skipping under load. Regular inspection, cleaning and small adjustments can keep everything running perfectly.

We will walk you through key maintenance tasks for both mechanical and electronic shifting systems, including how to inspect, maintain, and fine-tune each setup for precise and reliable gear changes, without the frustration of missed shifts, noisy pedalling, or chain drops.

a. Why Derailleurs & Drivetrain Maintenance Matters

  • Shift Quality
    • Precise shifting reduces chain wear and improves power transfer
    • Sloppy shifts can drop your chain or lead to cassette damage
  • Performance
    • Clean, well-aligned derailleurs respond faster and more reliably
    • Helps you stay in the right gear when it matters most
  • Durability
    • Prevents overuse of certain gears
    • Reduces wear on cables, chainrings, and cassette

b. What to Look Out For

During cleaning, rides or routine checks, inspect for:

  • Slow or hesitant gear changes
  • Clicking or noise in certain gears
  • Chain rubbing in the front derailleur
  • Chain skipping under power
  • Bent derailleur hanger
  • For mechanical: frayed cables or stiff shifter action
  • For electronic shifting: delayed shifting

c. Common Problems, Likely Causes & What to Do

Symptom Likely Cause What to Do
Chain skips under pressure Cable tension too low or worn cassette Adjust barrel tension or replace cassette
Chain won’t shift into large cog Low cable tension or limit screw Adjust tension or L-limit screw
Chain won’t shift into smallest cog High limit screw too tight Back out H-limit screw
Hesitation when shifting Dirty cables or incorrect indexing Clean cables and adjust indexing
Clicking noise in one gear Misaligned derailleur or cable stretch Realign derailleur or re-tension cable
Electronic delay or no response Low battery or connection issue Recharge or check connections
Chain rub in small/big gear combos No front derailleur trim (mechanical) Use trim adjustment or re-check limits

d. Contents

Lots of information in this post isn't relevant to all bikes, i.e different tasks are needed for mechanical or electronic shifting systems.

Please feel free to skip to relevant sections:

  1. Derailleur Alignment
  2. Setting Limit Screws
  3. Cable Tension (Mechanical only)
  4. Gear Indexing
  5. Front Derailleur Trim (Electronic only)
  6. Replacing Shifting Cables (Mechanical only)
  7. Troubleshooting (Electronic only)
  8. Lubrication & Final Check
  9. Top Tips Round-Up

1. Derailleur Alignment

Misaligned derailleurs are one of the most common causes of shifting issues. Checking and adjusting the position of both front and rear derailleurs ensures your bike shifts efficiently and safely.

The rear derailleur hanger is the small metal tab that connects the rear derailleur to your frame. It’s designed to bend slightly in a crash to protect your derailleur and small misalignments can cause poor shifting.

The front derailleur has a cage that should have outer edges parallel to the chainrings. The height of the cage should be about 1-3mm above the large chainring teeth.

a. What You’ll Need

  • Hex keys (usually 5mm)
  • Phillips screwdriver
  • Optional: derailleur hanger alignment tool

b. Rear Derailleur: Step-by-Step

  1. Stand behind the bike and look at the derailleur and chain, it should be that the jockey wheel is vertically aligned with the cassette and the chain is vertical.
  2. If it appears twisted or tilted, the hanger may need re-shaping or replacing:
    1. Small adjustments can be made by hand with derailleur in place, but we would recommend using a derailleur hanger alignment tool.
    2. If large adjustments needed, simply replace hanger (it is designed to be replaced after crashes).
  3. Use a derailleur hanger alignment tool (relatively cheap) to check and alter position accurately:
    1. Thread tool into the derailleur hanger.
    2. Rotate the gauge around the rim of wheel aiming for consistent gap.
    3. Use the arm of the tool as lever to gently bend the hanger at any point with inconsistent gap.
  4. To replace the hanger:
    1. Unscrewing derailleur from hanger, then hanger from frame.
    2. Attach hanger to frame, then derailleur to hanger.
    3. Check position and adjust position as needed.
  5. After adjusting derailleur hanger:
    1. Check limit screws - see section 2.
    2. Check cable tension (mechanical only) - see section 3.
    3. Check gear indexing - see section 4.

c. Front Derailleur: Step-by-Step

  1. From above, look down with your eye-line over the chainring and check outer edges are parallel to the chainring outer edges.
  2. From the front, check gap between front derailleur cage and top of large chainring teeth is 1-3mm wide
  3. To adjust position of front derailleur:
    1. Loosen the derailleur clamp bolt.
    2. Adjust position as required.
    3. Re-tighten lightly and re-check position from both angles.
    4. Tighten to correct torque (usually 6Nm but do check on carbon frames).
  4. After adjusting front derailleur position:
    1. Check limit screws - see section 2.
    2. Check cable tension (mechanical only) - see section 3.
    3. Check gear indexing - see section 4.

Note: If your front derailleur uses a band clamp with a separate shim for carbon or alloy frames, make sure to use the correct insert and check for slipping after test riding.

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2. Setting Limit Screws & B-Screw

Limit screws define how far the derailleur can physically move in either direction. They prevent over-shifting off the cassette or chainrings and should be set correctly on all derailleurs (rear, front, mechanical and electronic.)

The B-screw (B-tension screw) controls the gap between the upper jockey wheel and the largest cassette cog. It should be adjusted if your chain doesn’t clear the largest cog, you’ve changed cassette size or rear derailleur, you experience grindy, noisy, or hesitant pedalling in the largest cog. 

a. What You’ll Need

  • Bike-Stand (optional but recommended)
  • For Limit Screws:
    • Usually: #2 Phillips screwdriver
    • For some SRAM: 2.5mm Hex
    • For some Campagnolo: 3mm flat-head
  • For B-screw:
    • For Shimano: #2 Phillips screwdriver
    • For SRAM: 2.5mm or 3mm Hex
    • For Campagnolo: 3mm flat-head or Philips screwdriver

b. Limit Screws: Step-by-Step

  1. Whilst bike in stand, or on a short ride, check rear derailleur:
    1. If using a stand, inspect the position of derailleur whilst on smallest cog, then push derailleur to largest cog whilst turning pedal lightly, looking for position of resistance.
    2. If testing on a short ride, check shift into smallest cog and then all the way to largest cog, checking both these gear can be correctly found and if there is any resistance whilst riding in them.
  2. To adjust rear derailleur:
    1. Shift to smallest cog, turn H-screw until jockey wheel vertically aligned.
    2. Shift to largest cog, turn L-screw until jockey wheel vertically aligned.
  3. Check front derailleur:
    1. Shift to smallest cog, and then largest cog
    2. If you hear grinding in the smallest or largest gear, or the chain won’t shift onto them at all, the limit screws likely need adjustment.
  4. To adjust front derailleur:
    1. Shift to small chainring and smallest cog, turn L-screw until cage just clears the chain on left side.
    2. Shift to large chainring and largest cog, turn H-screw until cage just clears the chain on right side.

Note: Installing a chain catcher (especially on carbon bikes) can be helpful to prevent chain drop and frame damage.

b. B-Screw: Step-by-Step

  1. Check gap between top of upper jockey wheel and bottom of largest cog:
    1. Shift to the largest cog and smallest chainring.
    2. Check gap size for specific model:
      1. Generally around 5-6mm on Campagnolo
      2. Generally around 5-7.5mm on SRAM
      3. Generally around 5-6mm on Campagnolo (although they prefer not to state a ga and indicate smooth, quiet shifting is goal)
  2. Adjust B-Screw as required (typically at rear of derailleur):
    1. Turn clockwise to increase the gap (for wide cassettes)
    2. Turn counter-clockwise to bring the jockey wheel closer
  3. Check shifting between chainrings and larger gears:
    1. Set gap visually for smooth shifting to the largest cog without excessive pulley gap or chain noise.
    2. Pay extra care if using 11–34T or larger cassettes
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3. Cable Tension (Mechanical only)

Proper cable tension is essential for crisp, accurate shifting. If your chain hesitates, skips, or overshoots, tension is usually the culprit. Here's how to check it and adjust as needed on both front and rear mechanical derailleurs.

Most bikes come with a barrel adjuster that is turned by hand to fine-tune cable-tension and indexing. For this section, we will focus on larger adjustments made by adjusting the amount of cable tension held at derailleur.

Note: If you are adjusting cable tension, set all barrel adjusters to middle (neutral) position to allow tightening and loosing when fine-tuning and indexing.

a. What You’ll Need

  • Bike-Stand (optional but recommended)
  • To loosen cable pinch bolts
    • Usually: 5mm hex 
    • Some (cheaper) derailleurs: 4mm hex
    • Some (older) derailleurs: 10mm spanner
  • Cable puller (optional, but helpful for tensioning manually)

b. Shifter Cable Tension: Step-by-Step

  1. Check rear derailleur cable tension:
    1. Shift to the smallest cog and smallest chainring.
    2. Try shifting rear gears one click up while pedalling.
      1. If the chain hesitates or doesn’t shift up: tension is too low.
      2. If the chain jumps past a cog or double-shifts: tension is too high.
    3. Shift back to the smallest cog and smallest chainring.
  2. Check front derailleur cable tension:
    1. Shift to the smallest cog and smallest chainring.
    2. Try shifting to large front chainring whilst staying in smallest cog.
      1. If the chain hesitates or doesn’t shift up: tension is too low.
      2. If the chain is thrown off: tension is too high (or limit screw incorrect).
  3. To adjust with barrel adjuster:
    1. Make small adjustments (1/4 turns by hand) and test.
    2. Turn counter-clockwise to increase tension.
    3. Turn clockwise to decrease tension.
  4. To adjust manually on derailleur:
    1. Set any barrel adjusters to the middle (neutral position).
    2. Loosen cable pinch bolt on derailleur.
    3. Pull cable tighter manually or loosen by feeding cable back.
    4. Re-tighten bolt to correct torque (usually 5-6 Nm).
    5. Test shifting.

Pro Tip: It helps to pre-load a little extra tension into the cable before tightening pinch bolt and be careful not to overtighten.

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4. Gear Indexing

Gear Indexing refers to micro-adjustments to align the derailleur perfectly with each gear. When indexing accurate, every click on the shifter equals a crisp gear change, ensuring crisp and silent shifts between gears.

Most modern mechanical road-bikes come with a barrel adjuster that can be turned by hand to fine-tune cable tension. These can be located on derailleur, shifters or on the frame (normally on downtube or in cable stops.) Inline barrel adjusters (placed within cable housing) also exist and can be added if there is no fixed barrel adjuster, or if a secondary adjuster is desired (usually added during a shifter cable change.)

For electronic shifting systems, indexing is equally important and the positional alterations for fine-tuning are referred to as micro-adjustments. The process adjusts the derailleur's alignment with the cassette, just like mechanical indexing, but done digitally, with slightly different methodology for the different models/brands.

a. What You’ll Need

  • Bike-Stand
  • For mechanical:
    • Barrel adjuster
  • For electronic:
    • Manufacturer App
      • Shimano: E-Tube
      • SRAM: AXS 
      • Campagnolo: MyCampy
    • For some models: Junction box

b. Mechanical Shifting: Step-by-Step

Pro tip: Check your shifters are clean, crisp and operating correctly before indexing (see previous post on Cleaning You Road-Bike for details.)

  1. Whilst bike is in a stand, check indexing:
    1. Shift through gears with large then small chainring.
    2. Look for hesitant, delayed or noising shifting where chain rubs.
    3. If chain hesitates shifting to larger cogs, tension is slightly low.
    4. If chain hesitates shifting to smaller cogs, tension is slightly low.
  2. Fine-tune with barrel adjusters:
    1. Remember that adjustments will change whole derailleur.
    2. Make small ¼-turn adjustments and test.
    3. Look for smooth, quiet shifting.
    4. Turn counter-clockwise to increase tension.
    5. Turn clockwise to decrease tension.

c. Electronic Shifting: Step-by-Step

Pro tip: Check your shifters for moisture buildup and clean with dry microfibre cloth or soft dry brush before to ensure they are crisp and operating correctly before indexing.

  1. Make sure battery is fully charged and correctly working:
    1. Low batteries can affect shifting performance.
  2. Whilst bike is in a stand, check indexing:
    1. Shift through gears using both chainrings.
    2. Look for hesitant, delayed or clicking noises whilst shifting.
  3. Shift to middle cog (5th from top) and then enter micro-adjust mode:
    1. Shimano Di2: Press and hold button on derailleur or junction box until light changes colour.
    2. SRAM eTap/AXS: Hold button on rear derailleur until light flashes.
    3. Campagnolo EPS: Enter via app or press and hold mode button on shifter.
  4. Use your rear shifter to make small adjustments:
    1. Use the shifter levers to nudge the derailleur slightly inward or outward.
    2. Each press makes a tiny correction in position to all shifting.
  5. Exit adjustment mode:
    1. Either press the same button again or wait for the system to time out automatically.
  6. Test shifting across the cassette:
    1. Pedal and shift through all gears, one at a time.
    2. Aim for silent, fast movement with no rub and continue micro-adjusting if needed.

Note: Steps vary slightly between models: refer to your user manual or app for system-specific instructions.

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5. Front Derailleur Trim (Electronic only)

Trim refers to small, fine adjustments of the front derailleur position to accommodate the chain’s angle as it moves across the cassette. Without it, the cage can rub the chain in certain gear combinations, for example, riding in the big ring with larger cassette cogs, or the small ring with smaller cogs.

Different electronic groupsets handle trim differently, depending on generation and model. Most modern groupsets have an auto-trim function that automatically adjusts, so that manual-trims are only required during set-up.

Pro tip: If your chain rubs while in the big ring and small cog combo, try shifting out of that extreme gear combo and wait for auto-trim to take effect.

a. What You’ll Need

  • Bike-Stand (optional but recommended)
  • Manufacturer App
    • Shimano: E-Tube
    • SRAM: AXS 
    • Campagnolo: MyCampy
  • For some models: Junction box

c. Manual Trim: Step-by-Step

  1. Check if auto-trim will provide adjustments:
    1. Shift through gears using both chainrings.
    2. Look for chain rubbing in large-large or small-small combinations.
    3. Shift out of combination and allow for auto-adjustments.
    4. Check app and repeat.
  2. Only proceed with manual-trim if auto-trim is not adjusting or if setting-up.
  3. Enter set-up or micro-adjust mode:
    1. Shimano Di2: Hold button on derailleur or junction box until light changes colour.
    2. SRAM eTap/AXS: Hold button on rear derailleur until light flashes.
    3. Campagnolo EPS: Enter via app or press and hold mode button on shifter.
  4. Shift to big ring and mid-cassette and use your front shifter to make small adjustments:
    1. Use shifter to nudge the derailleur left or right (micro-moves).
    2. Each press makes a tiny correction in position to all shifting.
  5. Test shifting across the cassette:
    1. Pedal and shift through all gears, one at a time.
    2. Aim for silent shifting with no rub and continue fine-tuning if needed.
  6. Exit adjustment mode:
    1. Either press the same button again or wait for the system to time out automatically.

Note: Steps vary slightly between models—refer to your user manual or app for system-specific instructions.

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6. Replacing Shifting Cables (Mechanical only)

Replacing old or sticky cables restores crisp shifting and reduces friction, especially on high-speed systems like 11/12-speed. Inspect your cables regularly looking for rust, fraying, or resistance when shifting. If the lever feels rough or inconsistent, the cable may be worn or dirty.

Shifting cables can be routed internally or externally and the steps to replace alter. We recommend buying a suitable shifting cable replacement kit to ensure you have all components needed.

Whilst changing the cable, you may want to add or re-install an inline barrel adjuster for fine-tune gear index. It is rare that these are included in kits, but easily and cheaply available.

Notes on cable-replacement kits: 

  • Most Shimano/SRAM kits are cross compatible whereas Campagnolo cables have smaller heads (4mm rather than 4.7mm).
  • Some systems are fully sealed or include sealed ferrules to prevent water, salt or grit entering the system:
    • Especially good for winter, wet or gravel cycling.
  • Coated cables are smoother, but PTFE-coating can wear over time:
    • Polymer-coated would be our recommended choice.
  • Check length of cables needed (you can cut, but you can't extend).
  • Check length of housing sufficient (internally routed cables require more).
  • Check if housing included requires is pre-lubed.
  • Check required cable diameter (usually 1.1mm or 1.2mm).

Table of common cable-replacement kits:

Brand / Kit Routing Type Cable / Housing Length (x2) Compatible Groupsets Cable Type Housing Type Included Grease Recommended
Shimano OT-SP41 Shift Cable Set External 2100mm / 1700mm Shimano (All Mechanical) Pre-lubed stainless steel Compressionless, pre-lubed Ferrules, end caps No
Shimano Dura-Ace OT-SP41 (Internal) Internal 2100mm / 2000mm Shimano Dura-Ace / Ultegra / 105 (Mechanical) Polymer-coated stainless steel Compressionless, pre-lubed, extra length Sealed ferrules, end caps No
SRAM SlickWire Shift Cable Kit External 2200mm / 1800mm SRAM (All Mechanical) PTFE-coated stainless steel Compressionless, low-friction Ferrules, end caps Optional
SRAM Professional Shift Cable Kit Internal 2200mm / 2200mm SRAM Force / Rival / Red (Mechanical) Low-friction stainless steel Compressionless, low-friction Sealed ferrules, end caps Yes
Campagnolo Ultra-Low Friction Shift Kit External 2000mm / 1700mm Campagnolo (All Mechanical) PTFE-coated Campagnolo-specific cables Compressionless, low-friction Ferrules, end caps Optional
Campagnolo Ergopower Ultra-Shift Kit Internal 2000mm / 2000mm Campagnolo Ultra-Shift / Power-Shift Standard Campagnolo cable Compressionless, designed for internal routing Ferrules, end caps Yes
Jagwire Elite Sealed Shift Kit Internal 2300mm / 2000mm Shimano / SRAM (All Mechanical) Slick stainless steel Sealed compressionless, pre-lubed liner Sealed ferrules, end caps, liner No
Jagwire Pro Shift Kit External 2300mm / 1800mm Shimano / SRAM (All Mechanical) Slick stainless steel Compressionless LEX-SL, pre-lubed liner Ferrules, end caps No

a. What You’ll Need

  • Cable replacement kit
    • Cables (with sufficient length)
    • Cable Housing (with sufficient length)
    • End caps for cable
    • Ferrules (i.e. end caps for housing)
  • Inline barrel adjusters (if desired)
  • Cable cutters
  • For internally routed cables: Quality string (or similiar)
  • For kits that need greasing: Cable grease
  • Pick (or fine-point tool / pen)
  • Fine metal file
  • Hex keys

b. Cable Routing: Step-by-Step

Note: The frame can have sharp edges or tight entry points for internal routing. Use caution to avoid cutting yourself or fraying/damaging the cable during installation.

  1. Shift to smallest gear and set all barrel adjusters to middle (neutral) position.
  2. Start with rear derailleur cable
    1. If you cut too short, can then use for front derailleur.
  3. Cut off end cap and disconnect from derailleur.
    1. If internal routing, tape string to old cable.
  4. Remove cable from shifter:
    1. Remove handlebar-tape and shifter hoods as required.
    2. If internal routing, pull through cable & housing leaving string in place as guide for routing, taping the string at either end to avoid it in falling inside.
  5. Remove old housing:
    1. Use as template to measure new housing.
    2. Cut new housing to length.
    3. File end of new housing to smooth and slightly round.
    4. Use pick to open housing ends. 
  6. Feed cable through housing:
    1. Grease new cable lightly if required.
    2. Thread ferrules on cable before/after housing.
  7. Attach cable and housing:
    1. Attach to shifter and tape in place along bottom of handlebars.
    2. For externally routed cables: Attach housing to frame.
    3. For internally routed cables: Tape new cable to string and pull through frame.
    4. Measure required length to derailleur, making as short as possible without sharp bends.
      1. Some kits have special housing for this section.
    5. Affix ferrules.
  8. Clamp and tension to derailleur.
    1. Cut cable 2cm from derailleur and affix end cap.
  9. Replace handlebar-tape over shifter cable.
  10. Re-index rear-derailleur.
  11. Repeat steps 3-9 for front derailleur.

c. Adding Inline Barrel Adjuster: Step-by-Step

  1. Select location for Inline Barrel Adjuster:
    1. Look for a location without a major bend in the cable.
    2. Often near or parallel to a straight section of frame for support.
  2. Cut housing at chosen location.
  3. Install cable ends into inline adjuster, using ferrules as desired:
    1. Ensure adjuster is halfway open to allow tightening/loosening later.
  4. Test shifting and re-index rear-derailleur.

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7. Troubleshooting (Electronic only)

As with most electronics, it can take a little experience to diagnose issues. A general rule of thumb is to check the easiest fixes first, and only move onto more complex alterations as required.

a. What You’ll Need

  • Manufacturer App
    • Shimano: E-Tube
    • SRAM: AXS 
    • Campagnolo: MyCampy
  • For some models: Junction box
  • Dry cloth and brush for cleaning

b. Common Issues & Solutions

Issue Easy Solution Further Solution
No response Charge battery & check Firmware updates Check/replace CR2032 coin battery in shifters
Chain rubs or clicks Check auto-trim is active & then shift out from problem gear Check derailleur alignments & index gears 
Shifting feels sluggish Check plugs/wires & wireless pairing correctly connected Clean derailleur & slightly lube pivots

 

If any problem still exists, consult user manual or a bike-shop for further assistance.

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8. Lubrication & Final Check

Before finishing any maintenance task, apply light lubrication and confirm all systems work under load.

a. What You’ll Need

  • Clean, dry cloth or soft brush
  • Lubrication
    • Oil for pivot points
    • Chain lubrication (or wax)
  • Cloth for removing excess

b. Lubrication & Final Check: Step-by-Step

  1. Wipe or brush down any areas worked to remove debris, moisture or dirt.
  2. Add a drop of oil to derailleur pivot points.
  3. Wipe off excess oil to prevent dirt build-up.
  4. Spin through all gears under pedaling.
  5. Confirm no rubbing, skipping, or hesitation.
  6. Double-check derailleur alignments, limit screws and gear indexing.
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9. Top Tips Round-Up

  • The aim is always smooth and silent shifting
  • Replace worn hangers, bent ones are common after bike falls/crashes
  • Don’t overtighten limit screws, they only set the range
  • Check shifters are clean and crisp before adjusting gearing
  • Fine-tune indexing with small barrel adjuster ¼ turns or one micro-adjustment at a time

Continue reading with Brake System Maintenance

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