Indexing: How To Tune Shifting, Index Bike Gears & Derailleur Fixes In One Step

If your bike has shifting issues, check that the rear derailleur is properly indexed. A basic indexing adjustment is easy to do, and it will make your shifts fast and precise.

Indexing: How To Tune Shifting, Index Bike Gears & Derailleur Fixes In One Step

Written by
Bruce Lin

Published on

Posted in
Tech

When you shift gears, it should feel fast, crisp, and precise. But if your rear derailleur is making loud clicking noises, hesitating to shift, or even getting stuck in gear, you probably need to adjust your indexing. 

To the uninitiated, adjusting a rear derailleur is intimidating, but a basic indexing adjustment is actually simple. Anyone can do it! To help you dial in your shifting, I’ll explain what indexing is, how it works, and how you can tune it at home in only a couple of minutes. 

What is indexing?

When you shift gears, your shifter makes a click. The number of clicks your shifter has is matched with the number of cogs on your cassette. Each click pulls (or releases) a precise length of cable, specific to the compatible derailleur's geometry. As you might guess, that derailleur is designed to move the exact distance between two cogs on the cassette when it is shifted one click. 

Rear derailleur indexing explainedIndexing keeps the rear derailleur aligned with the cassette cogs when shifting.

Good indexing: The derailleur is aligned perfectly with each cog and your shifting is spot on. 

Bad indexing: The alignment between derailleur and cogs is off and your shifting suffers. 

Indexing goes out of alignment because the amount of tension in the cable is either too high or too low. This is usually due to things like cable stretch, wear and tear, and other environmental factors. Fortunately, it’s easy to adjust. 

[button]Shop bikes[/button]

How to adjust rear derailleur indexing and tune shifting

To adjust indexing and dial in your shifting on a cable-actuated drivetrain, all you do is turn the barrel adjuster. 

Rear derailleur road and gravel bike barrel adjusterThe barrel adjuster is a knob found at the end of the derailleur cable housing. On road and gravel bikes, it’s usually located at the rear derailleur. On mountain bikes, it’s usually located at the shifter. 

Mountain bike rear derailleur and shifter barrel adjusterThe barrel adjuster can be screwed in or out. When you do this, you effectively change the overall length of the cable housing, which increases or decreases the cable tension. Dialing in cable tension using the barrel adjuster is how you adjust indexing.

Here’s how: 

  • If the derailleur is struggling to shift down to the easier gears, turn the barrel adjuster counter-clockwise to add cable tension.
  • If the derailleur is struggling to shift up to the harder gears, turn the barrel adjuster clockwise to reduce cable tension. 

When doing this, make sure your drivetrain is clean and lubed. A dirty or unlubricated chain can have a huge effect on shifting performance. Check out our chain lube guide for more info. 

Adjusting indexing is easiest to do in a bike repair stand, or with a friend willing to hold your rear wheel off the ground. Spin the pedals and test the up- and down-shifts between two cogs. Many mechanics like to set the indexing at the top two cogs on the cassette. Observe which direction the derailleur needs help shifting, and turn the barrel adjuster a click or two at a time to adjust it. 

Rear derailleur indexing tuning and adjustmentThe goal is to find the perfect balance where up and downshifts are equally quick and precise. Once the shifting/indexing looks good between these two cogs, shift up and down the whole cassette to see how it performs. Make sure you can get in every cog, and fine-tune with the barrel adjuster if needed. 

Because the barrel adjuster is located at the shifter on a mountain bike, you can actually adjust your indexing while riding. If you want to adjust indexing on the fly on a road or gravel bike, you can add an in-line barrel adjuster to the derailleur cable housing near your cockpit.  

[newsletter]

Troubleshooting

If an indexing adjustment has gotten your shifting close, but it’s still not quite perfect, be sure to check your derailleur’s B-gap. Check out our B-gap guide for more.

There is also a chance that the indexing will seem perfect between two gears, but as you shift through the entire cassette, the derailleur will struggle to shift or get hung up on other gears. There are two common causes for this issue: 

  • Your cable and housing might be too old, worn, or contaminated. Freshen it up with a new cable and housing.
  • Your derailleur hanger is bent. If so, it needs to be straightened.

Hopefully, these tips help you improve your bike’s shifting. Checking and adjusting indexing is the easiest way to make sure your bike always shifts as well as it can, and I suggest doing it whenever you clean and lube your chain. Now get your indexing dialed and ride on!

More from Tech

  • Zwift vs. TrainerRoad Review: The Best Indoor Cycling App
    Zwift vs. TrainerRoad Review: The Best Indoor Cycling App
    Tech

    Zwift vs. TrainerRoad Review: The Best Indoor Cycling App

  • How To Change or Adjust Your Bike Stem
    How To Change or Adjust Your Bike Stem
    Tech

    How To Change or Adjust Your Bike Stem

  • The 10 Most Common Fixes on Used Bikes
    The 10 Most Common Fixes on Used Bikes
    Tech

    The 10 Most Common Fixes on Used Bikes

  • How To Install and Remove Bike Pedals
    How To Install and Remove Bike Pedals
    Tech

    How To Install and Remove Bike Pedals

  • I bought an open mold carbon frame from China. I wouldn’t do it again.
    I bought an open mold carbon frame from China. I wouldn’t do it again.
    Tech

    I bought an open mold carbon frame from China. I wouldn’t do it again.

  • Do Gravel Bikes Need Carbon Aero Wheels?
    Do Gravel Bikes Need Aero Carbon Wheels?
    Tech

    Do Gravel Bikes Need Carbon Aero Wheels?

  • Tubeless Tire Sealant Explained: Installing Tubeless Tires, Best Sealant & More
    Stan's tubeless tire sealant
    Tech

    Tubeless Tire Sealant Explained: Installing Tubeless Tires, Best Sealant & More

  • Rare Frame Spotlight: ENVE Melee
    Rare Frame Spotlight: The Fast and Versatile ENVE Melee
    Tech

    Rare Frame Spotlight: ENVE Melee

  • How To Measure and Replace a Bicycle Chain
    How To Measure and Replace a Bicycle Chain
    Tech

    How To Measure and Replace a Bicycle Chain

  • Bike Repair Costs: Budgeting For Bike Maintenance
    Bike Maintenance
    Tech

    Bike Repair Costs: Budgeting For Bike Maintenance

New Arrivals

SHOP BIKES

Newsletter Sign Up