What Is A Bottom Bracket On Your Bike?

The bottom bracket is something that a lot of bike owners are not aware of or know what a bottom bracket is on a bike. A good majority of bikers will never ready have to do anything with the bottom bracket, they only think it is the part that is used to connect the bike’s crankset to the frame, but it does more.

Yes, the bottom bracket connects the bike’s crankset to its frame but it also allows the crankset to rotate freely within the bike frame. It will have a spindle or an axle on the bottom bracket to which the crankset attaches. Bottom bracket bearings fit inside the bottom bracket tube, which connects the seat tube, down tube, and chainstays.

In this post, we will go through what is a bottom bracket on your bike. Let’s get started!

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What Is A Bottom Bracket On Your Bike?

The bottom bracket is a component that is inserted inside the bottom bracket tube. Simply the bottom tube is at the bottom of the bike frame that connects the seat tube, down tube, and chainstays.

The bottom bracket component itself connects the bike’s crankset to its frame which allows the crankset to rotate.

For the bottom bracket to be able to rotate they use parts called bearings. In modern bottom brackets, you will more than likely need to replace the bottom bracket if the bearings go bad. This is because of the current product design.

How Long Should A Bottom Bracket Last?

The bottom bracket like any other bike component has a life expectancy. When the bottom bracket starts to give trouble and the bearings start to make noises such as creaking sounds while you are pedaling. These could be signs that the bottom bracket may need to be replaced.

The failing bottom bracket can be replaced relatively quickly and a new bottom bracket part generally costs around $20. The average life span of the bottom bracket of your bicycle may vary.

For the low-end bottom bracket, it may be able to last for up to 6000 km. After that, it may start failing. While the Shimano brand can last up to 10,000 km. This factor also depends on how you use the bike and the maintenance.

Sometimes you can get unlucky and the bottom bracket might last maybe for only 500 km. The riding conditions and environments should be taken into account as they can affect the life expectancy of your bicycle’s bottom bracket.

How Do I Know If My Bottom Bracket Is Going Bad?

You can tell that your bottom bracket may need to be replaced when you start to hear noises such as creaking sounds when you are pedaling. You can also check the bottom bracket by dropping the chain off of the smallest chainring and then spin the cranks.

If there is movement such as side-to-side wobble, or grinding noises, or little clicks. Then it may be time to replace the bottom bracket.

Should I Grease My Bottom Bracket?

To help maintain and help bike components to last longer you should grease moving parts regularly, this includes the bottom brackets. The moving parts of your bicycle are continuously undergoing pressure.



Your bicycle’s parts especially the moving parts will eventually acquire rust, corrosion, and damage from constant usage. By applying grease on these moving parts especially the bottom bracket can delay the degradation of the sensitive moving parts of your bike.

For this reason, you should apply grease every once in a while to extend your bike’s bottom bracket life span.

What Are The Different Types Of Bottom Brackets?

There are 2 types of bottom brackets for bicycles. These are as follows.

  • Threaded bottom brackets.
  • Press-fit bottom brackets.

The threaded bottom brackets are threaded into your bicycle frame while the press-fit bottom brackets are installed by being pressed in on your frame. We will learn about these two types of bottom brackets to help you choose the best bracket which is suitable for your bike

The threaded bottom brackets are available in different versions. The cheaper ones as well as the older versions use bearings that sit inside the frame with a fixed axle that is tightened into the crank arms.

Meanwhile, the press-fit bottom brackets don’t need a threaded shell installed on the bike frame. This type of bottom bracket is becoming more popular nowadays. This lets designers make composite frames that do not need tough installation for the bearing to be installed.

Wrapping Up

Finally, I hope this article covering what is a bottom bracket on a mountain bike was helpful. The bottom bracket is inserted in the bottom bracket tube and the crankset connects to the bottom bracket which allows the crankset to rotate freely within the bike frame.

If it is a case that you are not sure if the bottom brackets need to be replaced you can visit your local bike shop.

And that’s it for now! I’d love it if this post on what is a bottom bracket on your bike was helpful to you. Let me know if you have any questions and let me know if there is more to add.

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Bottom Bracket On Your Bike