Unstable gears


Hi everyone,

I've got a Viking Safari folding bike. Recently I had to remove the back wheel to fix a puncture. Since then the gears are unstable in the sense that for certain gears, my bike kind of "wants" to put the next or previous gear. Sometimes it actually changes the gear without me doing anything !

What's the most likely cause of the problem and how to fix it ?


Senior Member
Assuming you have put the wheel back straight, it probably just needs a little cable tension adjustment. Just make a small adjustment on the barrel adjuster. This is best done on a stand so you can adjust the cable adjuster whilst turning the pedals. You will be able to tell when you have found the optimum position/adjustment.

Just double check that your wheel is on squarely beforehand though.


Ride It Like You Stole It!
South Manchester
The barrell adjuster is on the rear gear changer where the cable enters it.

If you look at the back of the bike, low down, you will see if the rear gear's jockey wheels are in line with the sprockets on the wheel - if it's slightly out, you need to turn the adjuster slightly. Tightening the adjuster clockwise will move the gear changer (called a mech or deraileur) towards the smaller sprocket. Turning anti-clickwise will pull the changer nearer the bigger sprockets.

If you need a video, gust google 'adjusting rear bicycle gears' or deraileur as they are known.
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