Slipping Gears & Cable Stretch

Slipping Gears & Cable Stretch

Slipping Gears and Indexing: Derailleur Geared Bikes

Normally with correctly set up derailleurs and properly tensioned gear cables, your bicycle gears are properly indexed, meaning each click of your gear shifter will cause a single shift of your gears.

However, soon after buying a new bike, or following a bike service you may notice a deterioration in gear performance: your rear gears may start ‘jumping’ or ‘slipping’; and/or your chain may start rubbing on your front derailleur when you are not riding in the extreme combinations (big front chain ring/big sprocket on cassette (and vice versa)). This means the gears are no longer ‘indexed’ correctly.

This is a normal part of the bedding in process and can be caused by:

  • gear inner wire stretching (this can even happen with ‘pre-stretched’ cables); and/or
  • the outer cable plastic ferrules slightly compressing and bedding into the frame cable stops.

But don’t worry, we’re going to show you in a few easy steps how to index your gears, and here’s the best bit, you don’t even need any tools to do it!

How to index your gears

  1. First of all you need to locate your barrel adjusters.

Rear gears

  1. With bikes with a barrel adjuster on the rear derailleur (see Figure 1). Start with your chain on the smallest sprocket on the rear cassette. Make sure you have completely down shifted on the shifter (so there are no more clicks left on the small paddle of your rear gear shifter).
  2. As you pedal along shift once (one click only) using the large paddle on your rear gear shifter. If your chain does not move up to the next sprocket or it is hesitant to shift, there is not enough tension in your gear cable.
  3. Shift back down one click by depressing the small paddle of your rear gear shifter once and check the chain is on the smallest sprocket.
  4. With your bike stationary, turn the barrel adjuster (figure 1) on your rear derailleur ¼ of a turn counter-clockwise. This will put more tension in your gear cable.
  5. Jump back on your bike and repeat step 3.
  6. If the gear shift has gone smoothly, congratulations, you have indexed your gears. If not, repeat steps 4 to 6.
  7. If your rear derailleur does not have a barrel adjuster (for example SRAM derailleur), you will need to use the barrel adjuster located on the gear shifter (figure 2), frame boss (figure 3) or inline gear cable (figure 4).

Front gears

  1. Start with your chain on the smallest (inner) front chain ring and smallest sprocket on the rear cassette. Also make sure you have depressed the small paddle on the front shifter so it has fully downshifted (until there are no more clicks).
  2. As you pedal along shift once using the large paddle of your front gear shifter (if your shifter has trim function you need to shift twice/give it a ‘big’ shift).
  3. If your chain does not move up to the next chainring or if it does move up but the chain is rubbing on the outer plate of the front derailleur, there is not enough tension in your gear cable.
  4. Shift back down by depressing the small paddle until the chain is back on the smallest sprocket and there are no more shifts/clicks when the small paddle is pressed.
  5. With the front gears you will need to use the barrel adjuster located on the front gear shifters, front gear cable frame boss or front inline gear cable adjuster.
  6. With your bike stationary, turn the barrel adjuster ¼ of a turn counter-clockwise. This will put more tension in your gear cable.
  7. Jump back on your bike and repeat step 2.
  8. If the gear shift has gone smoothly, congratulations, you have indexed your front gears. If not, repeat steps 4-7 again.

 

Trouble Shooting

If having carried out the above process and you are still having gear issues, we’d recommend one of our professional mechanics checks your bike over as there could be other reasons your gears are not indexing correctly. This could include:

  • Bent derailleur hanger or misaligned frame;
  • Worn/corroded gear cables;
  • Incorrectly set limit screws/B-tension screw;
  • Stiff chain link(s);
  • Worn/incompatible components, for example a new chain fitted to a bike with an old/worn cassette

On the rare occasion you are having gear issues following a service and the gear indexing procedure does not remedy the issue, don’t forget we offer a 3 month workmanship warranty and will happily remedy problems within warranty, arising as a result of the service.

Warning Note

With frame boss barrel adjusters (figure 3), be very careful if you cannot get the barrel adjuster to rotate in either direction. Do not try to force it or use tools such as pliers to turn it. We often see frame boss barrel adjusters that are seized in the frame, mainly due to corrosion. If you try and force a seized frame boss barrel adjuster, you can snap it in the frame leading to an expensive repair.

We hope you found this useful. Please do feel free to share it amongst your friends and/or on social media.

Best wishes and happy cycling!

The havebike team

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