Installing and Adjusting a Derailleur

To get the most out of your derailleur, it is important to make sure it is installed and adjusted properly.

Before You Install or Adjust

Before you install or adjust a derailleur, make sure these are addressed.

  1. Ensure the derailleur hangar is straight. This can often be overlooked or ignored. Whether your derailleur hanger is new or used, make sure its aligned with the frame using a good hanger alignment tool such as this one.
  2. Check for excessive drivetrain wear. Ensure there is not too much chain, cassette, or chainring wear. If any one of these is excessively worn, it can hurt shift performance and efficiency. 
  3. Ensure the drivetrain is clean. Chain, cassette, chainring cleanliness are important. If these have too much grit build up, it can hurt shift performance, efficiency, and life of the components. We recommend to brush debris that builds up on a cassette and chain after nearly every MTB ride.
  4. Ensure the chain is properly lubricated. Make sure the chain is properly lubricated.
  5. Ensure the chain length is correct. Most 1x drivetrains require the chain length to be within about 1 link of the ideal length. If you changed the cage size or pulley size during your rebuild, your chain length may need to change. Note: If you purchased a Madrone cage for a SRAM derailleur, and maintained the 12T/14T pulley sizes, you will not need to change your chain length. You will know if your chain length is incorrect, because the B screw setting may extreme, or the chain will not have tension in the small cog of the cassette, or be too tight in the large cog of the cassette.
  6. Ensure there is not too much friction in the links or cable. Friction in the link pivots, or in the cable and housing (for cable actuated derailleurs) will make it hard for the derailleur to move the right position during a shift. To address this, you may need to clean and carefully lubricate the link pivots. Ensure the cable and housing are free of pinch points, corrosion, excess friction, and frayed ends.

Adjustments

  1. B adjustment. The B adjustment is an important setting that affects how far the upper derailleur pulley is from the cassette. All derailleurs have some form of this, even T-Type. For wide range cassettes, it is especially important to set properly. On many derailleurs, it can go out of adjustment, and needs to be checked and re-set.
  2. MicroAdjust (or barrel adjustment) setting. This adjustment ensures that each shifter click is aligned with each gear on the cassette. On AXS derailleurs, it is set using the MicroAdjust setting in the AXS app. On cable actuated derailleurs, It is set using a barrel adjuster (which may be on the shifter or derailleur).
  3. Limit screws. There are 2 limit screws. They each prevent the derailleur from moving the chain off the outer-most gear on the cassette. Ensure the upper and lower limit screw are set properly.

How-To Videos

SRAM Specific

  1. SRAM AXS Eagle Derailleur Installation and Adjustment
  2. Pairing AXS Derailleur and Shifter
  3. SRAM Eagle Cable Actuated Derailleur Installation and Adjustment

General

  1. Park Tool How to Adjust a Rear Derailleur
  2. Park Tool Derailleurs and Shifting Playlist

Installation & Adjustment Summary

  1. Install the derailleur:
    1. Remember to use thread locking compound on this thread and all threads on the derailleur.
    2. Follow the SRAM torque specifications.
    3. Make sure the chain is routed properly over both pulleys and the cassette.
  2. AXS derailleur adjustment:
    1. Pair the derailleur with your shifter.
    2. Set both limit screws.
    3. Set the B screw adjustment using a SRAM gauge.
    4. Use the micro adjust feature on your AXS app to fine tune the shifting.
    5. Check the shifting in the stand and also while riding the bike. Often the micro adjust setting will be different by up to a few increments.
  3. Cable actuated derailleur adjustment:
    1. Set both limit screws.
    2. Set the B screw adjustment using a SRAM gauge.
    3. Set the barrel adjuster trim to match the shifter index points with each gear on the cassette.
    4. Check the shifting in the stand and also while riding the bike. Often the barrel adjustment setting will be off by 2 or 3 clicks.