How to Tell If Bike Crank Bearings are Bad

Bike bearings are more essential parts than you think. They help to rotate the crank, cassettes, wheel, and steering.

So, they have to go through pressure. Especially the crank bearings undergo extreme stress as the crank rotates the most while riding. As a result, bike crank bearings damage more than any other bearing.

However, when I am talking about cranks bearings, it actually refers to the bottom bracket. There are two sets of bearing on both sides of the bottom bracket.

When one of them gets damaged or worn out, inefficient peddling or cracking sounds occur. So, when the crank bearings are bad, you have to maintain or fix them. But, how to tell if bike crank bearings are bad? 

Well, this post is all about that. Keep reading to the end if you want to learn how to fix bad crank bearings.

How to tell if bike crank bearings are bad

Crank Bearings are Bad

You can tell it after the noise test. Firstly, set the bike on a Repair Stand. Then, shift the gear to the smallest chainring and remove the chain from the crankset. It is necessary because the sounds from other components (chain or cassettes) can disturb the process. Anyways, rotate the crank now and notice attentively. Can you hear something? If the answer is yes, then the crank bearings are bad.

It should be a quiet spin for good crank bearing. And, if there is a cracking or clicking noise, it’s a symptom of damaged or worn-out bearings.

How to keep bike crank bearings from damage

First of all, you have to be careful while installing a new bottom bracket or crankset. Sometimes, they are not seated correctly or tightened adequately.

As a result, it creates jerks, and the bearings get damaged. So, you must do it in the right way. However, I will explain the whole installation process in the next section.

Anyways lubrication is also crucial to keep the bearing from damage. It reduces friction and ensures smooth rotation of the crank.

So, apply Grease regularly to get rust-free bearings. Also, use it on the components (bottom bracket and crankset) while installing. Thus you can increase the durability of bearings.

You might be interested in why bike feel like it’s dragging

How to fix bad bike crank bearings?

When the problem is minor, you don’t need these steps to be done. But, if the crank bearing is too bad. These two easy steps can help to fix it. So, let’s do it.

Step-1: Removal of Bottom Bracket

Bike Crank Bearings are Bad

What was your observation on the noise test?

Was the sound smooth and even? If yes, the problem is minor, and it doesn’t need a fix. Just lubricate the bearing and conduct the noise test again.

If the noise is not gone, you have to repair or replace the bearing. The same goes for the result of creepy and uneven sound on the noise test.

However, let’s remove the bottom bracket and determine the condition of the bearings.

1. Firstly, loosen the crankarms with a Crank Wrench or Hex Key. It’s better to start with the right side as there has the chainring.

Then get a Crank Puller and screw it to the crank. Now, take a pair of Adjustable Wrench and unmount the crankarm. Similarly, unmount the left crankarm.

2. Secondly, go to the left side and remove the lockring with a suitable Bottom Bracket Tool. Also, take out the spacer, cup, bearing, spindle, and everything inside.

3. Lastly, clean all these parts with Degreaser Spray and wipe them with a clean rag. Now, the most critical job. Observe the bearings.

Is it too rusty or damaged? If yes, get a new suitable Bottom Bracket Bearing. Otherwise, just clean the old one and start the installation process.

Step-2: Installation Process

Before starting the installation process, know how to select the crank bearing. First of all, you will need a Bearing Gauge. You can measure the size of the bearing balls with it. After that, count the number of balls on the cage. That’s all. Now, you can get a bearing accordingly.

  1. Firstly, apply grease to the bearings, bearing cages, and bottom bracket cups. Then, go to the left side and thread the fixed cap first. Before that, set the bottom bracket shell and bearing correctly. Also, make sure the cup is not cross-threaded.
  1. Secondly, insert the spindle properly. Rember, the drive side of the spindle, is a bit longer than the non-drive side. However, seal the right side with the adjustable bottom bracket cup. Don’t forget to grease the threads and bearing before this. Also, make sure all the components sit correctly. Now, thread the lockring carefully and make sure it is not cross-threaded. Finally, tighten it with the bottom bracket tool.
  1. Lastly, you have to reinstall the cranks. Install the right crankarm first. For that, set it to the spindle and tighten it with the crank wrench. Then it’s time to install the left one. Mount it to exact 180 degrees with the right one and tighten it with the crank wrench. Finally, check the limit screw settings, and you are all set!

Frequently Asked Questions about Crank Bearings

Do bike cranks wear out?

Yes, bike cranks wear out at many points, especially on threads and bearing. As these points must carry extreme loads, it’s pretty natural that they will wear. You can’t stop it but can do damage control by regular cleaning and lubrication.

How long do bike crank bearings last?

Well, it’s tough to say. The durability of a crank bearing depends on many things, like the frequency or type of your ride. If you still insist, I would say you can ride over 5000 miles easily with a bike crank bearing. After that, it’s good to change the whole bottom bracket.

How much does it cost to get a new bottom bracket?

Again, it depends on the type of bottom bracket that suits your bike. If you ask, it will roughly cost around 30 to 50 USD, including the installation charge. But, if you can DIY the installation, it will cost even less; About 20 to 30 USD for a bottom bracket.

Can I change my bottom bracket type?

Most of the time, you can’t. There are compatibility issues with the bike. The type of your crank and the mounting system of the bottom bracket are the factors that work behind it. However, you can still replace the bottom bracket with one of the same tiers. But, the types are not swappable.

Conclusion

You can’t mobilize a bike without bearings. And good bike crank bearings are a must for them. When the crank bearings are not good, they fail to rotate the chainring well. As a result, you won’t get efficient peddling while riding.

Moreover, the bike will make unwanted noise which is very annoying. So, you must know if the bike crank bearing is bad and fix or replace them accordingly.

However, I have described above how to get rid of bearings problems. Take preventive measures so that you can ride more miles. When the bottom bracket gets exhausted, get a  new one and replace it.

I hope you ride with fun and efficiency.

Cheers!

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