“Indexing” your gears means aligning each click of the shifter with the precise vertical position needed for the corresponding derailed chain on the cog. If indexing is misaligned, you’ll typically experience skipping, rattling or reluctant shifts, or a chain that won’t stay on a gear. The great news: most indexing woes are a simple fix when you break out the barrel adjuster (minutes, not hours, usually), if the rest of your drivetrain is at least semi-healthy.

Before You Start Twisting: Are You Sure It’s Indexing?

Indexing woes tend to feel good: they’re a “tick” type, a “rasp” type and the chain doesn’t want to settle into a gear appropriately plainly. That is, it consistently is on the “between” gear, tick/Rasps along in that spot, or delays half a second, with the same slow down on say the middle cog several times whilst riding. But, if it’s definitely “skipping” under pressure, most of the time it might be a bad parts concern rather than an indexing issue.

• Most likely cause: cable tension too low, or cable/housing friction

  Best next step: add cable tension in 1/4 turn or less increments; may need to inspect or replace cables when shifting is inconsistent

• Most likely cause: cable tension too high, or derailleur can’t spring back due to cable routing friction

  Best next step: reduce cable tension in 1/4 turn or less increments; check for sticky cable routing on the top of the derailleur

• Most likely cause: index is slightly off (easiest to adjust!)

  Best next step: micro-adjust barrel adjuster in 1/4 turn increments

• Most likely cause: worn cassette cogs and/or worn chain

  Best next step: measure the wear of the chain itself; repeat for the cassette cogs’ wear; if needed, replace either.

• Most likely cause: bent derailleur hanger

  Best next step: check hanger alignment (might need to access a few special gauges, but your job will be easier, then!)

• Most likely cause: cable friction from housing rubbing under load (compression), or perhaps that parts are loosely fitting

  Best next step: inspect derailleurs, cable routing (especially at the end), and where it goes into and out of housings; check the looseness of the derailleur mounting, and if needed, lube the chain somewhat.

Two fast checks that save tons of time

• Check the derailleur hanger from behind; if the derailleur cage is even slightly tilted toward the wheel… or toward… well, farther away from it that also should incline the index to NEVER be perfect, etc.
• Even small visual problems like frayed strands, cracks, rust, or drag: frayed cable strands, cracked housing, rusty cable, or gritty/draggy feel usually means it’s time to replace cables and housing (indexing will drift and feel inconsistent until you take care of this).

Tools and Setup (What You Actually Need)

• Bike stand (not required; you can flip the bike on its side carefully or use some alternative to a workstand)
• Correct screwdriver or hex key for derailleur limit screws (depends)
• Hex keys for cable pinch bolt (usually 4-5 mm, verify)
• A clean rag and a little lube for the chain (dry noisy chain acts like poor shifting)
• Optional, helpful: chain wear checker, and/or torque wrench if you’re doing complete setup

How to Index the Rear Derailleur (There’s Steps in Here Too)

Most “skipping and poor shifting” complaints come from rear derailleur. Rear indexing is primarily a matter of cable-tension adjustment using a barrel adjuster (either at derailleur, shifter, or inline on the housing). Limit screws and B-tension matter too—but not the first dial you turn if you’re just after routine indexing.

Step 1) Start in the right gear

1. Shift front to large chainring (if you have more than one on the front). Drops some tension on the rear. That will make it easier to try the adjustment.
2. Shift rear to smallest cog (hardest gear).Keep clicking the shifter until you cannot click anymore—that ensures you’ve released the shifter all the way.
3. Pedal with your hand and listen. The drivetrain should be silent on the smallest cog. If it won’t go onto the smallest cog, stop and check the high limit screw and/or excessive cable tension.

Step 2) Confirm the high limit (H) is preventing over-shifts (not the cable)

The H-limit screw is supposed to restrict how far the derailleur can travel outward (toward the dropout) so it doesn’t drop the chain in-between the smallest cog and the frame. It’s a safety setting, and if the cable is holding it away from the stop you can pretend you have “thought” the H-limit is set correctly when it isn’t.

1. While at the smallest rear cog, decrease the amount of cable tension on the derailleur by turning the barrel adjuster in the direction that loosens the cable (often clockwise, but think: you want LESS tension).
2. Watch the derailleur settle outward, and let it click to rest against the stop.
3. Adjust the H screw so that the top pulley now sits directly in line with the smallest cog, and pedal. Make sure the chain runs relatively quietly and isn’t trying to fall off the outside.

Step 3) Index the gears with the barrel adjuster (the core fix)

Indexing is matching derailleur position to the shifter clicks. The barrel adjuster does this by changing effective cable tension. (Note: Don’t sweat the “perfect” alignment on just one cog: your goal is the best shifting across the cassette.)

1. From the smallest rear cog, click the shifter once to go to the second-smallest cog.
2. If the chain doesn’t climb to the next cog (or hesitates), increase cable tension slightly (often by turning the barrel adjuster counterclockwise), and try again.
3. If the chain climbs too far for a 1-click shift, or sounds like it’s trying to climb farther than you commanded, reduce cable tension slightly (often by turning the barrel adjuster clockwise).
4. Make small changes—start with 1/4 turn (or one “click” if your adjuster is indexed).
5. Once the 1-click shift is crisp, shift one gear at a time across the cassette (to larger cogs). Listen for ticking/rubbing in each gear, and note any gear that’s slow to engage.
6. Then shift back down the cassette (to smaller cogs) one at a time. Downshifts should be quick and decisive—if downshifts are slow, you usually have too much tension and/or cable friction. (Note: a simple rule that works on nearly every mechanical drivetrain: If having a problem shifting to LARGER rear cogs: add tension. If a problem shifting to SMALLER rear cogs: reduce tension.)

• If neither direction leads to a consistent result (especially if it changes gear-to-gear) suspect a bent hanger or cable/housing friction rather than “more indexing”.

Step 4) Set low limit (L) safely

The L-limit screw is your safeguard against shifting the chain off the largest cog into the spokes of the rear wheel. You generally set this after indexing comes close, because the tension you apply to the cable determines how far the derailleur can move inward. So:

1. Shift carefully into the largest rear cog (at the back) while pedaling slowly.
2. Check the L screw, you ideally want the top pulley positioned directly under the largest cog and not able to move inward any further when under increased pressure from the shifter.
3. If the chain is struggling to reach the largest cog, don’t just back the L screw out a ton, first check indexing (tension) and hanger alignment. An L screw backed off too far is a spoke hazard.

Step 5) Check for B tension (pulley-to-cog gap) for crisp shifting on big cogs

The B-tension setting determines how close the upper derailleur pulley is to the cassette. On some derailleurs, if the clearance is too tight when you shift to the largest cog, it can feel rough or even noisey. Too much clearance, and the shift can feel vague—and on wide-range cassettes, this can become more paramount. To set:

1. Shift yourself (contents shift yourself) and to the largest rear cog and the smallest front chainring (or easiest gear up front). Ta da.
2. See how far apart the upper pulley and the largest cog are.
3. Turn the B-screw. Is it tighter? Looser? You’re looking for a sound-ish place and for it to feel sound. You’ve probably valet parked it. Would that be wifi?After significant B-screw change, also check indexing across the cassette—changing derailleur body angle can change the feel of your shifting.

Front Derailleur Indexing (If You Have 2x or 3x)

Since the front shifting seems to get blamed for many indexing issues, be aware that front derailleur position (height/rotation), limit screws and cable friction are the most common culprits. Some front shifters DO have an indexing or “trim” position(s); others, though not “indexing”, are friction (not “indexing”);

Front derailleur basics (the 60-second checklist)

• Cage height: the outer cage plate should sit just above the big chain ring teeth (close, but not touching).
• Cage angle: the cage should sit “parallel” to the chain rings.
• Low limit: prevents the chain from dropping “inside” (toward the bike frame).
• High limit: prevents the chain from being “too far in/out” and overshifting left or riding off the big ring.
• Cable tension: fine-tunes where in that window you want it to shift faster/slower (and to reduce rubbing, once limit screws’ correctly).

Micro-adjust the front (when you have rubbing or slow shifts)

1. If you find the chain hesitates going to the big ring, that usually means a SLIGHT increase in cable tension (with the front barrel adjuster if you have it).
2. With the above being adjusted correctly, and if the chain is rubbing the outer cage plate when you’re in the big ring, that should indicate a SLIGHT increase in cable tension or, use of trim (if your shifter has that).
3. If you do use trim, check if chain rubs at all with back frears and now in the easier ones. But if so, you may have cable tension too stiff; try decreasing it—then confirm if your low limit is correct.

If the barrel adjuster is maxed out (all the way in or out), reset it: thread it back around halfway, re-clamp the cable at the derailleur and then fine-tune.

Common Mistakes That Make Indexing Worse

• limit screws used to “fix” and “tweak” hesitations: these screws are safety stops, not ‘fine’ tune.
• turning the barrel adjuster 2–3 full turns at once: go for 1/4 turn steps (or one click) and re-test!
• Ignoring cable friction: old housing, rust, dirty cable guides = inconsistent shifting that no indexing can fix. And don’t forget to also check the tension between shifter and derailleur (the cable run.)
• Skipping hanger alignment after having a crash/tip-over; a slightly bent hanger can give the appearance of bad indexing on multiple gears.
• Chasing perfect quiet in extreme cross-chain gears: noise/rub may be normal gene in extreme gear combos; stick to how the bike rides normally throughout the range of gears.

How to Verify the Fix (A Repeatable Test Ride)

• In a safe place – shift one gear at a time up (to larger cogs) the cassette under a light pedaling pressure; every shift should complete quickly and quietly
• Shift one gear at a time down (to smaller cogs) the cassette; downshifts should be quick, and should not “hang” on a larger cog.
• Add moderate load (gentle uphill or slight acceleration). If it skips under load – only on one 1 cog, suspect a wear rather than

Lastly, test the two extremes (smallest and largest rear cogs) thoroughly. If the chain threatens to shift off the cassette at either extreme, stop and adjust limit screw.

WHEN INDEXING ISN’T ENOUGH (AND WHAT TO DO INSTEAD OF TEARING YOUR HAIR OUT)

• Bent derailleur hanger: Usually need to be measured and straightened with a hanger alignment gauge (or by a local bike shop).
• Worn chain/cassette: If the chain is skipping under power on a specific cog, you may want to measure chain wear and/or check for “shark fin” teeth on that cog.
• Worn derailleur pivots or pulleys: Excessive play can preclude proper indexing even with a respectable pair of new cables just installed.
• Incompatible parts: Mismatched shifter/derailleur pull ratios (certain shimano style) or incorrect housing material and inner/outer tube sizes can prevent proper indexing.
• Shifter problems: the inner guts of your shifter can wear out or get contaminated, and if clicks are missed or there isn’t enough movement in the indexed movements, cable movement will be unreliable.

FAQ

References

1. Park Tool: Rear Derailleur Adjustment (limit screws, indexing, B-screw) — __URL0__
2. Park Tool: Rear Derailleur — Advanced Troubleshooting — __URL1__
3. Park Tool: Rear Derailleur Hanger Alignment — __URL2__
4. Sheldon Brown: Derailer Adjustment (including indexing) — __URL3__
5. SRAM: Rear Gear Adjustment (mechanical systems and barrel adjusters) — __URL4__
6. SRAM Support: Barrel adjuster use for SRAM Eagle derailleur — __URL5__
7. Park Tool: Front Derailleur Adjustment — __URL6__
8. Park Tool: Front Derailleur — Advanced Troubleshooting — __URL7__
9. Bicycling: How to Adjust a Front Derailleur — __URL8__