How to Adjust Rear Derailleurs on a Bicycle

If you notice any hesitation while shifting gears on your bicycle, a rear derailleur adjustment may be needed. When one of the shift cables stretches, the derailleur isn't able to move far enough when you try to shift the bike. Here is a simple explanation about how to adjust your rear derailleur.

Difficulty: Moderately Easy

Instructions

High and Low Adjustment

1. Turn the bike over so it is resting on its handlebars. Prevent the bike from falling over by putting a block of wood against the handlebars.

2. Start the high adjustment by spinning the pedals with one hand to turn the rear wheel and shifting the front derailleur to high. Shift the rear derailleur into high gear with the other hand.

3. Use the barrel adjustors to loosen the cable if the chain doesn't grasp the smallest cog. Turn the barrel adjustor in a clockwise direction to make the cable lengthen. Shorten the cable by turning it counter clockwise if the chain goes beyond the smallest cog.

4. Implement the high set screw when the chain is close to the smallest cog. Loosen the high set screw 1/4 turn if the chain won't go easily. Turn the pedals continuously and shift up and down while turning the screw until the chain goes smoothly into the smallest cog.

5. Observe the rear derailleur and make sure the cog and the small pully wheel match up. Tighten the high set screw if the chain goes beyond the cog.

6. Begin the low adjustment by spinning the wheels with one hand and shifting the front derailleur to low with the other hand. Shift the rear derailleur towards the largest cog, and keep the wheel moving at all times. Be aware not to overshift as this could cause the chain to get caught in the spokes.

7. Tighten the low set screw if the chain touches the spokes. Persist with shifting up and down and spinning the pedals. Turn the screw at the same time until the chain gets to the largest cog.

Cable Tension Adjustment

8. Shift the front derailleur into high first, and then do the same with the rear derailleur. Adjust the rear shifter until it clicks once, moving the chain up one cog. Spin the barrel adjuster to the left if it doesn't shift.

9. Retighten the adjusters if the cable still doesn't work. Pull some slack out of the derailleur by loosening the cable fixing bolt. Alter the tension in the cable until it is smooth.

10. Shift to the large cog in the rear and the small chain-ring in front. Shift up and down one gear in the back and adjust until smooth.