MTB gears jump - what to do when the gears are stuck

BIKE

· 22.12.2022

MTB gears jump - what to do when the gears are stuck

Photo: Georg Grieshaber

We show you how to fix the most common problems with mountain bike gears.

Rattling chains and crashing gear changes are almost as horrible as the drilling noise at the dentist. The gears only shift smoothly when all the parts of an MTB gear system work together perfectly. We show you how to fix the most common problems with mountain bike gears.

Contents of this bike service article on MTB gears:

How to keep the gears shifting: avoid chain rattling, adjust the front derailleur and rear derailleur

Derailleur hanger - bend or replace?

When shifting up, there is a hitch or the chain even skips a gear: Then you should take action, search for the fault and readjust the gears on your mountain bike if necessary.

Photo: Wolfgang WatzkeWhen shifting up, there is a hitch or the chain even skips a gear: Then you should take action, search for the fault and readjust the gears on your mountain bike if necessary.

In our E-MTB special "All the facts for beginners" you will find even more useful information:

>> Brake workshop: Quick help for grinding disc brakes <<

>> Cassette workshop: Changing the sprocket - how-to instructions & tools <<

>> Puncture repair on the road: How to repair tubeless tyres in seconds <<

MTB gears: The right basic setting

Shimano MTB drivetrain: Adjusting the front derailleur

Chain rattling and jittery gear changes can spoil the best tour. If you make the right adjustments, you can significantly improve your shifting performance in just a few steps. We show you how to make your chain run quietly and smoothly. - Hans-Peter Ettenberger, BIKE laboratory employee

Photo: Georg GrieshaberHans-Peter Ettenberger, BIKE laboratory employee

1. height clearance: If the chain is on the largest chainring, there should be a gap of one to three millimetres between the outer guide plate and the teeth of the large chainring. The thickness of a folding rule segment usually just fits between the guide plate and the large chainring. The height of the front derailleur can be adjusted using the fixing screw of the front derailleur on the frame.

2. adjust the inner end stop: The screw for the inner end stop is usually located on the outside. However, it is worth taking a look at the operating instructions. Shift the chain onto the largest sprocket of the cassette. Now adjust the inner limit stop so that the chain does not rub against the inner guide plate. If you turn the screw clockwise, the derailleur moves outwards, i.e. away from the frame.

3rd tension: Shift the chain to a smaller sprocket. Now use the derailleur shifter to shift the chain onto the large chainring. If the chain does not climb, gradually increase the tension by turning the adjusting wheel against the direction of travel.

4. adjust the outer end stop: If the chain skips the large chainring to the outside when shifting, you must reduce the outer limit stop. To do this, turn the screw next to the screw for the inner end stop (usually the inner screw) anti-clockwise. In the heaviest gear, the chain should no longer rub against the outer guide plate of the front derailleur.

5. skewing: With double gears, extreme skewing of the chain (small chainring, small sprocket or large-large) should be avoided in order to protect the chain.

6 Images

Photo: Georg Grieshaber

MTB derailleur adjustment: How-to guide

1. hanging up the bike: An assembly stand is an ideal aid when adjusting the gears. If you don't have one, hang the bike with the saddle on a bar. This allows you to turn the crank with your left hand and operate the gear lever with your right.

2: Distance: Rear derailleur and sprocket One of the prerequisites for optimum gear shifting function is the correct distance between the rear derailleur and sprocket. This is set using the wrap screw near the derailleur hanger. The distance varies depending on the model. Check the operating instructions!

3. outer end stop: To set the outer end stop correctly, it is important that the shift cable is completely slack. To do this, loosen the clamping screw on the rear derailleur. If you turn the upper stop screw to the right, the rear derailleur moves inwards. The perfect position is reached when the upper derailleur pulley and the smallest sprocket are exactly aligned. Now clamp the derailleur cable again.

4. adjust the cable tension: The adjustment screw on the shift lever regulates the tension of the shift cable. It is responsible for ensuring that the chain climbs smoothly from one sprocket to the next when shifting gears. To increase the tension, turn the adjusting wheel outwards, in this case in the direction of travel. If the chain skips a sprocket when you shift into an easier gear, the tension is too high. In this case, turn the screw in.

5. check alignment: After adjusting the tension, shift all the way up until the chain is on the largest sprocket. The largest sprocket and the derailleur pulleys should be exactly aligned.

6 Images

Photo: Georg Grieshaber

Tips for adjusting MTB gears: Distance between rear derailleur & cassette

Some spacing rules have not only applied since corona. As described below, the slightly different distance between the rear derailleur and cassette, depending on the model, is important for the proper functioning of the rear derailleur on a mountain bike gear system.

Sram offers a plastic mounting gauge (Sram Chaingap Tool) for its Eagle 1x12 MTB rear derailleurs. This allows the distance from the rear derailleur to the sprocket set to be set precisely >> To the instructions.

Defect and wear Is the rear derailleur still not working despite correct adjustment? This may be due to a bent derailleur hanger.

Further reasons can be worn chains or sprockets. Dirty or worn shift cables also impair the shifting function.

Different distances between rear derailleur and cassette - with the Sram mounting gauge you can easily adjust your Sram Eagle rear derailleur.

Photo: Georg GrieshaberDifferent distances between rear derailleur and cassette - with the Sram mounting gauge you can easily adjust your Sram Eagle rear derailleur.

MTB derailleur hanger: bend or replace?

The derailleur hanger connects the frame and the derailleur on the bike - the rear derailleur to be precise. If the derailleur hanger - which is usually made of aluminium and is intended to protect the frame in the event of a fall - is badly bent, you will hardly be able to shift gears. The best thing to do is to get yourself a replacement derailleur hanger just in case (note: varies depending on the manufacturer and model!) and put it in the tool compartment of your bike rucksack.

The derailleur hanger is an inconspicuous part of the mountain bike that is often responsible for the derailleur not working properly. However, you notice it immediately if it is bent or broken.

Photo: Max FuchsThe derailleur hanger is an inconspicuous part of the mountain bike that is often responsible for the derailleur not working properly. However, you notice it immediately if it is bent or broken.

What is a derailleur hanger on an MTB and when does it break?

A derailleur hanger can be found on every bike. It is often overlooked. And yet it has a crucial function. The derailleur hanger acts as a predetermined breaking point between the frame and the rear derailleur. It is designed to protect both from major damage if the derailleur gets caught on a root or branch, for example. This is why the derailleur hanger is made of brittle material. If the load is too high, it breaks. But it can also bend before it cracks. The mountain bike derailleur then only works to a limited extent, as the alignment of the rear derailleur and sprockets is no longer correct. Sometimes derailleur hangers are even slightly bent when new. To carefully align them, it is best to work with a special alignment tool. If they are badly bent, it is better to replace them.

To align the derailleur hanger, the rear wheel must sit straight in the frame and there should be no lateral runout. Then use the alignment gauge to measure the top and bottom of the rim. If the derailleur hanger is straight, the distance between the gauge and the rim should be the same everywhere. If not, bend the derailleur hanger carefully.

Photo: Georg GrieshaberTo align the derailleur hanger, the rear wheel must sit straight in the frame and there should be no lateral runout. Then use the alignment gauge to measure the top and bottom of the rim. If the derailleur hanger is straight, the distance between the gauge and the rim should be the same everywhere. If not, bend the derailleur hanger carefully.

If the derailleur hanger is badly bent or broken, the only solution is to replace it. Depending on the bike frame, there are countless types of derailleur hanger. It is best to have one in reserve before the defect occurs. When fitting, observe the manufacturer's torque specifications. If necessary, apply medium-strength Loctite to the screw.

Photo: Georg GrieshaerIf the derailleur hanger is badly bent or broken, the only solution is to replace it. Depending on the bike frame, there are countless types of derailleur hanger. It is best to have one in reserve before the defect occurs. When fitting, observe the manufacturer's torque specifications. If necessary, apply medium-strength Loctite to the screw.

Home

MTB gears jump - what to do when the gears are stuck

MTB gears: The right basic setting

Shimano MTB drivetrain: Adjusting the front derailleur

MTB derailleur adjustment: How-to guide

Tips for adjusting MTB gears: Distance between rear derailleur & cassette

MTB derailleur hanger: bend or replace?

What is a derailleur hanger on an MTB and when does it break?

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