Bicycle Rear Wheel Bearings Loose? Do This (5 Steps)


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Bikes start to feel wobbly and make clicking noises once in a while. The bike moves to and fro, and it is difficult to control it or make precise movements for tricky turns or descents. Not only is that annoying when taking your bike out for a spin, but it’s also dangerous.

If you are experiencing these problems with your bike, there’s a good chance you may have loose ball bearings on either wheel. Loose ball bearings cause the wheel to become wobbly and make your bike feel unstable. Luckily, ball bearings can be tightened with some quick work.

In this article, I’ll guide you on how to fix loose ball bearings in the rear wheel. I focus on the rear wheel because it has some extra components to look after, although the process is not too different from that of the front wheel.

Bicycle rear wheel bearings loose

Fix Your Loose Rear Wheel Bearings in These 5 Steps

The process to repair a rear wheel bearing is mostly the same for the front wheel.

However, there is one difference. The front wheel has a smaller hub that is accessible from both sides of the wheel.

On the other hand, the rear wheel has a cassette that obscures the axle cone located on that side. To access the axle cone on this side, you will have to remove the cassette.

Here’s a guide on how to remove the cassette.

However, you can always make adjustments to the axle from another side of the wheel if you feel that you do not need to adjust the side with the cassette.

Steps 1 and 2 are basic steps. Steps 3 to 5 are helpful for a thorough servicing.

Tools that you Need

  • Cone wrench (for axle cones). Check the length of the wrench (in mm) so that it matches your cone size.
  • Hex wrench or adjustable wrench (for the lock nuts).  The second wrench is needed to hold one component while adjusting or removing another one. This is very important as it helps you to adjust screws and cones properly, and with higher accuracy than using your hands.
  • Degreaser (for ball bearings)
  • Light cloth (for cleaning crease)
  • Grease (for re-greasing the hub)
  • Screwdrivers and pliers for handling components

1. Remove the Lock Nuts

Use the cone wrench to hold the axle cone, and the other wrench to hold the lock nut.

Rotate the lock nut counterclockwise (or clockwise if necessary) to loosen it. You can then unscrew it by hand.

If the lock nut is too loose, it means that the corresponding side needs adjustments. If the lock nut is too tight, then you should consider making adjustments to the other side before proceeding. If the lock nuts on both sides were tight, then you should check if your axle cones need readjustments.

Tip: Take note of the order of the screws and fittings of your bike. If you are unsure that you will remember the arrangement, taking a photograph with your cell phone camera helps.

2. Adjust your Axle Cones

The next step is to see if your axle cones are too far away from the ball-bearing cup.

To check this, you need to rotate your cone using the cone wrench to bring it closer to the ball bearings.

Before you start, make sure that the axle is stationary to prevent it from rotating as you try to adjust the cone. You can do this by holding the axle from the other side with your hand.

You can also use a drill press vise to hold the axle and rest the wheel in a hormonal position to make things easier.

Once you have adjusted the axle, check if:

  • The axle is rotating smoothly. If it is not, it means that the cone is pressing against the ball bearings and causing too much friction. Loosen the cone if this happens.
  • The axle is wiggling between the walls of the bearing and displaying any play. If this is happening, that means you need to tighten the cone.

Repeat the process of tightening and loosening. Once you have adjusted the cone in the right position that enables the best movement without a wobbling axle, lock it in position by screwing back the lock nut.

Tip: Sometimes screwing that lock nut loosens the cone, causing it to wobble again. It is a good idea to tighten the axle cone to a slightly higher degree to give some room for readjustment when you fasten the lock nut again.

3. Remove the Hub and Clean It

Sometimes removing the bearing completely can help you to check if it is in good condition. Clean the ball bearings and other bearing parts using a degreaser and light cloth.

Check if all components, like cups, disks, and ball bearings are unbroken.

Depending on the type of free hub, you may need to replace broken components in your hub or replace it entirely.

It’s worthwhile to replace the ball bearings once or twice a year. They get worn out easily. 

You can purchase magnetic ball bearings online or from a nearby bike shop. Be sure to check which size is needed for your bike’s bearings. 

Tip: Use a magnet or magnetic screw to easily extract them from the hub casing.

Tip: Some bearings come with small components like rubber rings and dust capes. Use a flat-tipped screwdriver to pry them from their position to avoid damaging them.

Ball bearings on rear wheel of a mountain bike
Ball bearings should be replaced about once per year as a minimum for optimum performance

4. Grease the Components

Once you have separated and cleaned all the parts of the hub, you can apply grease to different parts.

For greasing the hub, add the grease inside the race.

Then place the ball bearings inside it. The ball bearings should form a circle around the edge of the race. Grease inside the hub functions as a lubricant for the axle.

You should also add a thin layer of grease to the axle.

This helps to minimize corrosion from wear and tear that can happen as the axle comes into contact with the ball bearings.

5.  Refit the Hub Parts

Start with the cassette side, and then move to the other side.

Similar to step 2, you will need to use two wrenches to keep the neighboring nuts or pieces stable as you adjust a component. Readjusting the axle again takes some trial and error to get the right settings.

You should make sure that the axle can rotate smoothly to allow the wheel to move freely. Make sure that all small components like spacers and nuts are nicely aligned.

Tip: When you are adjusting the bearing for a bike that has a quick-release mechanism, adjust the axle to a slightly loose fit. This is because when the quick release is fastened, it compresses the axle towards the ball bearings. So if you adjust the axle too tightly, it can become stiff.

Types of Bearings

There are different types of bearings in modern bikes (Source). Understanding the type of bearing helps you to figure out what you need to do in case it gets loose. Here are two of the most common types.

 Loose ball bearingsCartridge bearings
Mechanism·  Loose ball bearings placed in a cup
· A cone is used for preloading force
·  Ball bearings are placed in a cage between two rings(races)
·  Open-piece unit
·  Two seals on either side to keep out dust
Used inEntry-level bikesMid-level to competitive bikes
MaintenanceEasy to MaintainDifficult to maintain
AssemblyEasy to fully assemble and adjustCannot be adjusted or completely disassembled
Sizes· Based on ball bearing diameter
· 3 standard sizes: 3.969 mm (steerer, fork, pedals)
· 4.762 mm (front wheels), 6.35 mm (rear wheels)  (source)
· Based on inside and outside diameters, and width (eg. 5x24x5mm)
· Accompanied by standard identifiers for bore size and properties. (eg. 6802RS)
· Multiple standard sizes. (source)

In general, both types of bearings can perform well. Loose ball bearings are cheaper to maintain and can be adjusted with tools.

On the flip side, cartridge bearings can be easily damaged and require a complete replacement for your hub.

What Is The Main Difference In The Rear Wheel?

The Rear Wheels Have a Freehub

The rear wheel of a bike is usually the same size as the front wheel, but it differs in other ways.

First, the rear wheel hub is different from the front hub. It allows the real wheel to rotate freely, so the rider does not always have to move the pedals. This is why the rear wheel hub is also called the freehub.

Secondly, the rear freehub features a bigger cassette that holds the bicycle chain in place. Rear wheel cassettes include multiple sprockets to provide stability. 

Another difference is the ball bearings that help the axle to rotate smoothly.

Rear wheel ball bearings are larger (1/4’’) in comparison to front wheel bearings (3/16’’) (Source). The rear wheel also has 9 bearings compared to 10 in the front.

Types of Freehubs

There are different types of freehubs such as:

1.    Shimano

2.    Campagnolo

3.    SRAM 

It’s important to know what mechanism each freehub type uses and whether their parts are compatible with each other. While some of these freehubs use similar mechanisms, the dimensions of their components may vary.

Why Do The Rear Wheel Bearings Keep Getting Loose?

Mechanical Action

Over time, the components of the rear wheel bearing keep moving due to prolonged mechanical action. The axle is usually kept in position in between ball bearings with the help of cone screws and lock nuts.

These components can become misaligned because of vibrations and friction between the ball bearings and the axle.

When this happens, the axle becomes loose and starts to move sideways along the shaft of the hub.

Poorly Adjusted Screws

A very common problem with bike wheels is misaligned screws.

In these cases, your ball bearings may be working fine, but the cones, spacers, and nuts that hold the axle in place may be too loose.

Adjusting screws requires the use of at least two wrenches at a time, moving in opposite directions. Sometimes the screws are adjusted using only one wrench, or with bare hands. This results in some components not being tightened enough.

So when the bike is put to the test, the parts loosen up further.

A Damaged Axle or Hub

This is self-explanatory, but it does happen.

A broken axle may not be able to remain stable. Similarly, a broken hub or worn-out ball bearings will be unable to hold an axle in place.

These situations require a complete replacement of your axle or bearings.

Diagnosing a loose bearing on your bike’s rear wheel

To confirm that your wheel is wobbling, follow these steps.

1.    Check if your wheel nuts on the sides of the hub, and quick release are fastened tightly.

2.    Hold your bicycle frame with one hand and the top of your rear wheel with the other. Make sure your bike is in a stable position.

3.    Try to move your rear wheel to and fro along the axis of the hub shaft. The movement is also accompanied by a clicking sound.

If you see that your wheel is moving a lot, it means that you have a loose bearing. You need to get to work on fixing it!

Conclusion

Loose ball bearings are a common problem for older bikes that have seen a lot of action. An instinctive reaction is to replace it, but we all know that this is an expensive solution. The good news is that you can fix this problem with a bit of tinkering.

Martin Williams

Martin has been tearing up all sorts of trails on a range of bikes ever since he was young. He once cycled across France, and once fell into a canal on a hybrid. He writes about everything to do with cycling on our site. You can find out more about him at bicycle2work.com/about-martin-williams/

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