Adjusting the derailleur on a bicycle chain drive is not difficult.The first time it takes a little patience, but with some practice the derailleur is set up quickly.
In this how-to, we assume that the drivetrain is already installed on the bicycle and that the shifter cables and housings are undamaged.If the cable housings are damaged or rusty from the inside, the shifter cable cannot move properly in the housing and adjusting the derailleur will not help.The correct adjustment of the derailleur is done with three bolts.On the derailleur itself, three things can be adjusted, upper limit, lower limit and the body angle.You use the limits to set the maximum movement of the derailleur.This means that you make sure that the chain does not move past a cassette sprocket and fall off.
For this reason, the derailleur upper pulley wheel, or guide pulley, must be positioned exactly under the respective sprocket in the largest and smallest gear.The body angle is used to adjust the distance of the guide roller to the largest sprocket of the cassette.
How do I adjust the derailleur on my bike?
You must shift to the largest pinion before adjusting.The bolt for adjusting the upper limit (i.e. the lightest gear) is marked with an "L" on SHIMANO.If you turn this bolt clockwise, the derailleur moves away from the cassette.If you turn it counter-clockwise, the derailleur moves toward the cassette.The derailleur is in the correct position when the upper pulley forms a vertical line with the largest sprocket.
Step 2: Adjust the lower limit
To adjust the lower limit, shift to the smallest sprocket, or the hardest gear.To adjust the lower limit, turn the bolt marked with an "H" on SHIMANO derailleurs.When the bolt is turned clockwise, the derailleur moves to the right and is moves away from the cassette.In reverse, the derailleur moves to the left when the bolt is turned counter-clockwise.The lower limit is correctly adjusted when the lower pulley forms a vertical line with the smallest sprocket.
Step 3: Adjust the body angle
Step 1: Adjust the upper limit
A "B" on SHIMANO drivetrains refers to the bolt that is intended to adjust the body angle.The body angle is used to adjust the distance between the guide pulley and the largest sprocket of the cassette.With an optimally adjusted body angle, the guide pulley is about 5-6 mm away from the largest sprocket.
Step 4: Adjust the cable tension
On most bikes, you can set the tension of the shifter cable by means of the shift levers.The adjustment is located where the shift cable is moved into the shift lever.By turning you change the length of the Bowden cable, turning you forward will reduce the tension.If you turn backwards, the shifter cable is tightened.
Cable tension – what does it do?
Tension is one of the most important parameters for a well-functioning chain drivetrain.For this purpose, the shifter cable must be able to move cleanly in the housing.If not, you should first change the Bowden cables and housings.However, we are talking about the cable tensions and its effects on shifting performance.Depending on the tension, the derailleur behaves differently:
Tension is too low:
- If the tension is too low, the derailleur no longer shifts to the next largest sprocket correctly or at all.
- When you shift down a gear does the derailleur skip a sprocket?This is also a sign of a shifter cable that is too long.Although the limits are adjusted correctly, the derailleur no longer shifts to the largest sprocket?Then the shift cable is too long.
Tension is too high:
- The derailleur does not shift to the next smallest sprocket.
- The derailleur skips a gear during shifting up.
Adjusting your derailleur is quite simple.For optimum adjustment, a maximum of 3 screws must be turned and the cable tension adjusted.Check out our instructions on adjusting a derailleur and try it for yourself.
If adjusting the derailleur does not work as described, there may also be another issues, such as a bent derailleur hanger.However, fixing this needs some special skills.Therefore, we recommend that you go to your bike dealer with such problems.
With the right tension, we hope you have a lot of fun on your well-maintained bike.
Other issues
Adjusting a derailleur - this is how it works
Tip for easier limit adjustment: Something to help remember:The drivetrain always moves parallel to the direction of rotation of the limit bolts.
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