Bicycle Derailleur Adjustment | Causes and solutions for a maladjusted change

The adjustment of the bicycle derailleur can be very simple if we know what we are doing, or it can become a real headache for not knowing how to find the key or, why not, for things that are beyond normal adjustment.

In general, the big and best-known brands, such as Shimano and Sram, have a similar procedure when it comes to adjusting their bicycle gears, always with some differences.

We are going to stick to modern models, such as Sram Eagle and Shimano 12v bike derailleurs, but they are not too far in fit from older or more basic models or road bike derailleurs.

Table of Contents

Causes and solutions of a maladjusted change

We take it for granted that we are all very careful and keep our bicycles up to date, replacing components of our transmission when we must and with the chain and other parts clean and greased.

Mismatches due to damaged components

Indispensable for the proper functioning of a bicycle gear, although many times we find frayed cables inside the cable sheath or in the gear lever entry: our bicycle will not shift well, quite the opposite, for not to mention the imminent cable break, so we're going home in little crown.

Other many, or very many times, we find deviated derailleur hanger (the part of the frame where the derailleur is screwed on), either due to a blow, fall, transportation, etc. Shifting a bike with the frame hanger off will shift, but it will shift poorly. It will be necessary to align it with the corresponding tool in order for the derailleur to work as it should again.

The problems of a poorly adjusted change

That said, we are going to start with imbalances and disarrays that we can find, so that all of us, to a greater or lesser extent, can feel identified.

the chain jumps

Many times we find that the chain jumps, the chain does not sit well on each crown, it makes noise when pedaling or the chain does not go up or down the crown easily. It is the problem most demanded by users who come to our workshop with problems adjusting their bicycle derailleur.

On many occasions, it is enough to adjust the tensioner of the gear lever: clockwise to loosen the cable if our problem is that the chain has a hard time lowering the crown, or, counterclockwise to give more tension to the cable in the event that our chain has a hard time climbing crowns.

The chain does not go up or down at all

Sometimes the derailleur of our bicycle works well on small sprockets and poorly on large sprockets, or vice versa, it works well on larger sprockets and very poorly on smaller sprockets. In the event that our bicycle is making it so difficult for us, it is not necessary to hate cycling or change bicycles or replace the complete transmission, there is a solution.

If the chain does not finish going down to the smallest crown or does not finish going up to the largest crown, we will have to use, in the case of our Sram derailleur, an allen key 3, or an allen key 2 in case from Shimano, and turn the two small screws that we will find in our derailleur marked with H and L (High-Low), long gears and short gears respectively (small crown or large crown, to clarify).

The chain overflows to the crown

If our problem is that the chain gets between the small crown and the frame, we will have to tighten the screw marked with H to tell the derailleur not to go down as much, but without going too far or the chain will not go down to the small crown, the other problem we might run into, in which case we'd have to loosen it up.

The same happens in case the chain slips between the largest crown and the spokes; in this case we will have to tighten the screw L, again without overdoing it. In the event that the chain does not raise the largest crown, we must do the opposite, loosen the screw.

Sheave rub

On the other hand we have the adjustment of the distance from the change to the cassette. Sometimes we find bicycle derailleurs that when climbing crowns, especially in the largest ones, the upper derailleur pulley touches the crown when we go up a gear, even with the largest chain on the crown, said pulley is continuously touching it, increasing the wear of these elements, inaccuracies in the change and unwanted noises. Again, we don't need to throw expletives into the air or change transmissions.

Solution in SRAM: In the case of Sram, it is best to use the special tool, the typical piece of red plastic (blue in the case of the adjustment of electronic AXS models) or the latest version in white.

With the chain on the largest sprocket and placing said tool in position, we will see the marks of the tips of a sprocket on it, to match the tips of the large sprocket on our Sram Eagle cassette.

With the latest version of this tool, the white one as we have said, the chain must be in the second largest crown, and with everything in its position, make the tip of the tool coincide with the center of the screw of the upper sheave of our change.

Solution in Shimano. On the other hand, in Shimano 12-speed gears, it will suffice to match the small mark engraved on the inside of the castor holder at the top, with the edge of the largest crown of our cassette.

conclusion

Many are those who pass by our workshop tormented and desperate due to the malfunction of their bicycle derailleur when, in some cases, it is enough to check all these adjustments that, with a minimum of patience and tools, we can do at home.

Other times, or in case of desperation, we will have to go to a professional to assess the state of our transmission.

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