Why is my cassette wobbling?

We all know a wobbling cassette can be really annoying. On one hand, we are unsure if it is safe to bike with the cassette wobbling and on the other hand we are unsure as to what is causing the cassette to wobble. This article will answer all your questions related to cassette wobbling. As regular bikers, we often come across issues related to cassettes and believe it or not, cassette wobbling is quite common. If you have recently come across this problem and looking for solutions, you have come to the right place. We will address the common causes of cassette wobbling and give practical solutions. So if you are wondering why is my cassette wobbling, wonder no more.

Why is my cassette wobbling?

Cassette can be wobbly due to a number of reasons. We will look at the most common causes and some rare ones. This will hopefully help you determine why your cassette is wobbling and you will be able to fix the issue.

Cassette is loose

This is a common reason as to why the cassette may be wobbling. During installation, you may have not tightened the cassette fully. Overtime, this causes the the cassette to unscrew and become loose. This leads to it being wobbly.

This is too basic to be true but believe it a lot of people face a wobbling cassette only to realize that the cassette was loose. You can simply tighten the cassette and that should do the trick. To tighten the cassette, simple remove the rear wheel. Slide the cassette tool in the space where the cassette cutout is. Using a wrench, rotate the cassette clockwise. This should tighten the loose cassette. Put the wheel back on the bike. You should see that the cassette is no longer wobbling.

No spacers present

Another common cause of a wobbling cassette is lack of spacers. This is a bit technical, so let me explain. A lockring is used to secure cassette to the hub. If the cassette is too narrow for the hub, it will not be possible for the lockring to secure the cassette. To stop this from happening, a spacer is needed.

Hub size may vary

Your cassette may be wobbling due to the variation in the hub size. Even a minor size variation of 1mm could cause the cassette to wobble. This variation in the hub size causes the cassette to move up and down while you are pedaling. If the hub and cassette are of exact size, then you won’t face this problem. This variation is usually down to manufacturing but if you purchase your bike from a well reputed brand, this should not be an issue.

Rear axle may be bent

The wheel axle is where the hub and the wheel rotate and make the bike go forward. In case the axle is bent, both the wheel and the hub will be wobbly as they would be rotating around a bent axle. Your axle may be bent due to the bike falling on a hard surface. Whatever the case may be, a bent rear axle will cause the cassette to wobble. Unfortunately, the only solution for a bent rear axle is to replace it.

Hub bearings may be too tight

Hub bearing play an important role in the rotation of the rear hub around the axle. If the hub bearings are too tight, it will it quite difficult for the hub to rotate freely. You need to find the right balance. If the bearings are too loose, the hub won’t be stable. Ultimately, hub bearings being too tight or loose will end up making the cassette wobble. So you can adjust the tightness of the hub bearing to solve the problem of cassette wobbling.

Lockring may be bent

Just like the rear axle being bent, a lockring being bent will also cause the cassette to wobble. The lockring is used to secure the cassette to the hub. If the lockring is bent, it will not be able to secure the hub and the cassette. The solution to a bent lockring is to buy a new one. Lockring is inexpensive so it should not take a lot of your pocket.

Final Thoughts

We hope this article answers your question “Why is my cassette wobbling?” Many cyclists are a bit wary of a wobbling cassette. The last thing you want is to meet up in an accident due to a wobbling cassette. However in most cases, wobbling cassettes should not be a cause of concern. You can easily fix the problem of wobbling cassette by going through the common causes mentioned above. Sometimes, a wobbling cassette may indicate a deeper problem. In that case, it is much wiser to take the bike to a mechanic rather than fixing it yourself.

About the author

John Tomac

John Tomac is a retired American professional cyclist who is considered one of the greatest mountain bikers of all time.

He won numerous national and international titles during his career and also competed in road racing events such as the Tour de France and the Giro d'Italia.

Tomac now works as a coach and commentator and is also involved in charitable organizations that support disadvantaged youth and promote the sport of cycling.

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