Before you start troubleshooting: Clean the circuit meticulously and give it a new coat of grease. If this does not help, you will find the solution here.
How to rectify the following faults on the gears of your mountain bike:
1. the chain jumps and climbs reluctantly onto the next sprocket.
You can use the adjustment screw on the shifter to tighten it while riding (anti-clockwise). The screw on the rear derailleur also has some play. If this is not enough, you must loosen the cable and readjust it.
2. the chain jumps irregularly over the sprocket set.
There is dirt or small knots in the cassette. Remove these.
3. you must constantly readjust the circuit.
The cable is not screwed on tightly enough and is slipping very slowly. Tighten the cable.
4. the gearstick only works well in one part of the sprocket.
The cassette must be compatible with the rear derailleur. SRAM cassettes do not work with Shimano rear derailleurs as the sprockets are spaced differently. Therefore, you can only shift a few gears cleanly. Use a cassette that is compatible with the rear derailleur.
5. the chain slips.
Increase the wrap of the chain (you can find the instructions for this on p. 53, point 4 in our guide "The ultimate bike workshop"). If this does not help, the chain or sprocket is worn. Unfortunately, there is still no uniform standard for measuring wear. As a rule of thumb, you should not be able to lift the chain more than five millimetres off the chainring towards the front wheel. Otherwise, replace the chain. If there is no peace and quiet, a new sprocket is also needed.
6. the gearstick lever is stiff and the gearstick is reluctant to shift down.
A typical problem of dirty or kinked cables. Fit new cables and sleeves. When buying new cables, make sure that they are sealed against dirt. If the levers work again but the rear derailleur remains tired, the rear derailleur spring is worn out. You will then need to fit a new rear derailleur.
7. the gearstick cannot be adjusted.
You follow the adjustment instructions meticulously, but it doesn't work? Take a look at the derailleur hanger. It must be straight under the dropout. If it is only slightly bent, you can carefully bend it back. Be sure to remove the rear derailleur. Good bike workshops have a straightening tool with which they can realign the derailleur hanger perfectly.
8. the chain jumps rhythmically.
Check the chain for stiff or bent links. Stiff links can be made smooth again with a little oil and bending them back and forth from side to side. Bent links must be replaced. Always use the manufacturer's special pin for riveting.
9. the chain jumps on the lower sprockets.
If the cassette is compatible with the derailleur system, the bottom sprockets may be loose. Tighten the sprocket bolt.
10. the chain does not climb onto the next chainring.
The tension on the derailleur is too low. Tighten the screw on the gear lever. Otherwise you will have to loosen the cable and tighten it again with more tension.
11. the chain grinds on the derailleur.
You have adjusted the front derailleur correctly, but the chain rubs against the outer guide plate, especially when pedalling. This causes flex somewhere in the rear triangle or on the crank. Give the front derailleur a little more leeway than described in the workshop.
You can find more tips on all repairs to your mountain bike in our guide "The ultimate bike workshop".
