Adjusting the rear derailleur
This procedure explains how to adjust the rear derailleur so the chain can shift smoothly up and down the gear sprockets.
You need a small screwdriver to carry out this procedure. The chain, sprockets and cables must be clean.
This procedure is for a popular brand that has a H screw and an L screw. You must remember that these screws must only be adjusted to align the smallest and largest rear sprockets with the derailleur. They have no effect on the shifting action between sprockets. The shifting action is indexed in the shifting lever and this ensures that the chain engages the individual sprockets correctly.
- Raise the bike to an easy position for working and so you can turn the crankarm and operate the gears. Stand behind the bike so you have a good view of the rear derailleur.
- Shift the chain to the largest chainring and the smallest rear sprocket.
- Use the H screw to align the guide pulley of the derailleur exactly under the smallest rear sprocket. This prevents the chain from falling between the smallest rear sprocket and the frame.
- Shift the chain to the largest rear sprocket and use the L screw to align the guide pulley of the derailleur exactly under the largest rear sprocket.
This prevents the chain from falling between the largest rear sprocket and the spokes.
- Shift back to the smallest rear sprocket and then shift to the smallest but one sprocket. If this is not smooth, turn the adjustment bolt at the end of the cable to tighten or slacken the cable as required. Because the shifting system is indexed, all the sprockets should now engage correctly.
- Shift to the next sprocket and check that shifting is smooth. If not, turn the adjustment bolt on the cable slightly.
You may want to adjust the position of the guide pulley under the sprocket case. See the separate procedure for this.
