Why Is My Cassette Wobbling?

We all have that one bike we can’t just throw any cassette on without worrying about it wobbling. Usually, this happens when your cassette is loose or there’s a bad tooth that’s preventing the cassette from being perfectly straight. It’s not only a pain to deal with, but it can also cause some pretty serious damage if left uncared for long enough.

This is why we’re going to go over its causes and how you can fix a cassette so it’ll NEVER wobble again.

Is Cassette Wobble Normal?

Cassette wobble is a common problem with many bicycles. It’s caused by a loose cassette or chainrings. This wobbling can be quite annoying, but it does not usually affect the bike’s performance.

However, it can lead to more SERIOUS problems in the future. Worn-out parts can break and cause accidents and injuries. If you have noticed this problem with your bike, it is important to take care of it immediately. 

Also read: Why are bike Disc Brakes Pulsing

Should My Cassette Wobble?

If your cassette is wobbling or if it feels loose, you need to get it fixed or replaced right away. It could be a sign that there are problems with your bike and that it needs to be serviced.

It could mean that the bearings have worn out. The freehub body is designed to take the load of pedaling forces exerted on the cassette, but if there isn’t enough grease or too much pressure is being applied to the component, then this can cause it to wear out QUICKLY.

The result is that the wheel will begin to move slightly as you pedal and may even feel like it’s going out of true as well. This can also cause damage to other parts of your bike as well as making riding uncomfortable for you and dangerous for others who share the road with you.

What Causes A Bike Cassette To Wobble?

The cassette is the cluster of gears at the rear of your bike. It has several smaller cogs that are connected and spin around a larger cog called the ‘free hub’.

Also read: Bike making popping sounds

If you’re having problems with your cassette, it can be down to any number of things. We’ve listed the most common causes below so you know what to look for.

Poorly Adjusted Chainrings or Cogs

The first thing to check is whether the chainrings and cogs are well-adjusted. If they’re too far out, or one of them is bent, it will cause the cassette to wobble.

Poorly Adjusted Chainrings cause cassette wobbling

Poorly Adjusted Tensioner

A poorly adjusted tensioner is another common cause of cassette wobble. This usually happens when one side of the tensioner has been tightened too much, causing it to bend outwards and put pressure on the axle spindle.

The Chain Is Worn Out or Damaged

If the chain is worn out, it will slip on the sprockets, which can cause the cassette to wobble. You should check your chain regularly and replace it when needed (usually every 1,000 miles). If you’re unsure how to do this, we have an article on how to change a bike chain here.

Worn out chain cause cassette wobble
Worn out chain

The Hub Has Worn-Out Bearings 

A worn-out hub will also cause your cassette to wobble because there won’t be enough resistance from the bearings. This will result in them spinning freely rather than being engaged by a gear.

Bent Axle Spindle

The final cause of cassette wobble is a bent axle spindle. This can happen if you crash with your bike and hit something solid at speed, such as a rock or tree stump.

The impact can cause the spindle to bend slightly and make contact with the bottom bracket area when you pedal backwards – causing further damage in that area as well as creating an imbalance between the two sides of your bike’s drivetrain system.

How Do You Fix A Wobbly Cassette?

The first thing to do is check the tightness of the bolts on your derailleur. If they’re loose enough that you can move them by hand, then tighten them up with a socket wrench or Allen key.

Once you’ve done that, here are some other things to try:

  • Check your chain length. If it’s too long and is sagging under your weight, it’ll cause problems with shifting and will wear out your cassette faster than normal.
  • Check that nothing’s caught between the teeth of the cassette – especially if you’re riding in mud or sand – and clean out any grit before trying again.

However, If you suspect your cassette is loose, 

Make sure to check the lock ring – especially if it’s an old one or has been replaced with a cheaper alternative (e.g. aluminum instead of steel).

Test that the lock ring is tight against the frame/bottom bracket shell (where your chainrings are bolted on). If necessary, get some more grease on there and give everything another good tightening up. 

Before you start trying to fix it, though, make sure that your bike hasn’t been damaged in any way since its last service. If there’s any chance that something else might be causing your problem, then get it checked out by an expert before attempting any repairs yourself!


Can a cassette come loose?

A cassette can come loose and its very common issue faced by lots of cyclists. If the cassette moves (even a little) its loose.

Should there be movement in the rear cassette?

No there should not be any movement in the rear cassette if it is installed properly.

Certified bike mechanic based in Orlando, Florida. With over 15 years of knowledge and experience in the industry, I can help you diagnose issues and fix them.

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