BMX Tips

4 Most Common BMX Bottom Bracket Types

bmx bottom bracket types

Are you also wondering what are the common BMX bottom bracket types?

Hint: There are four.

At the core of your bike is the bottom bracket, a component you might not see much of but definitely feel in every pedal stroke.

So, what exactly is a bottom bracket or BB?

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It connects the crankset to the bike and allows you to pedal easily.

It’s the pivot point around which your legs spin, transforming your energy into motion.

The bottom bracket ensures your ride is smooth, your pedals are stable, and your bike is ready to take on everything from ramps to dirt jumps and streets.


Bottom brackets have evolved significantly over time.

From the early, more straightforward designs to today’s sophisticated setups, BBs have transformed to meet the demands of modern BMX riding.

Stay tuned as we delve deeper into the most common types of BMX bottom brackets. Understand the differences and choose the perfect one for your ride.

If you need a new BB, I have a list of the best BMX bottom brackets already prepped for you.

Understanding Bottom Brackets in BMX

If you’ve ever wondered what makes your BMX bike tick (or rather, pedal smoothly), the BB is your answer.

It’s not really visible (hiding behind the cranks and sprocket), but OH-SO-important.

A bottom bracket is the cornerstone of your BMX bike’s drivetrain.

It’s tucked away in the bike’s frame at the junction where the crank arms meet. It allows you to pedal with ease and grace.

Think of it as the wheel’s hub but for your pedals.

Bottom Bracket Components

A bottom bracket comprises several key components, each playing a pivotal role.

You’ve got the bearings, which reduce friction and make your pedaling as smooth as butter.

Then there’s the spindle, also known as the axle, which is the core that connects the two crank arms.

And let’s not forget the dust cups. They cover the bearings and protect them from dirt/dust but, at the same time, make everything look cleaner.

You’ll also usually get an aluminum dust spacer, but modern frames no longer need it.

The 4 Most Common BMX Bottom Bracket Types

1. Mid Bottom Bracket (Mid BB)

mid bmx bottom bracket

The Mid BB is a sleeker and more modern take on the bottom bracket.

Currently, this is the most common in freestyle BMX.

This type has gained popularity for its straightforward design that fits neatly into the bike frame without additional cups.

It’s like the streamlined, no-nonsense cousin of the American BB.

Pros: The Mid BB is known for its simplicity and ease of installation. Its lighter weight makes it a hit among riders looking for efficiency and speed.

Ideal scenarios: If you’re into competitive racing or love pulling off tricks where every ounce matters, the Mid BB could be your ticket to victory.

2. USA/American Bottom Bracket (American BB)

usa american bmx bottom bracket

The classic American BB is known for its sturdy and reliable design.

This type of bottom bracket is like the comfort food of the BMX world – it’s been around for ages and has a certain nostalgic charm.

The American BB is designed to take a beating with its larger bearings housed in metal cups.

But is it really stronger than a Mid BB? I don’t think so.

Pros: Its robust design can handle stress, making it great for hardcore tricks and jumps. Plus, it’s relatively easy to service, which is always a bonus.

However, the American BB can be a bit heavier than other BMX bottom bracket types, so the industry transitioned to the Mid BB.

3. Euro Bottom Bracket (Euro BB)

euro bmx bottom bracket

Taking a trip across the pond, the Euro BB offers a traditional approach with its threaded design that screws directly into the bike frame.

Pros: The Euro BB is praised for its precision and compatibility with many standard road and mountain bike frames, offering a snug and secure fit. In BMX, you can mainly find it in racing.

However, its complex installation process might be daunting for beginners, and it’s not as widely used in modern BMX designs.

4. Spanish Bottom Bracket (Spanish BB)

spanish bmx bottom bracket

Lastly, the Spanish BB brings a touch of flair with its unique design, featuring slightly smaller bearings than the Mid BB, all snugly fitted into the frame.

Fly Bikes (which is a brand from Spain) brought this version of a BB to the market but it didn’t stick.

Even Fly Bikes frames now have Mid BB.

Pros: The Spanish BB is known for its sleek design and lightweight, making it a favorite among riders who prioritize agility and aesthetics.

But its specialized bearings and sizing mean that compatibility and replacement parts might be more challenging to find.

Conclusion: Master BMX BB

And there you have it, the grand tour of BMX bottom bracket types!

Although four are available, you will mostly use the Mid BB version.

However, always check what BB your frame has (especially if you bought a complete bike), so you don’t get the wrong one.

Note: Nope, bottom brackets aren’t compatible with each other.

As we wrap up, think of your bottom bracket as the heart of your BMX bike, quietly working away to keep you moving smoothly and efficiently.

Keep riding, keep exploring, and most importantly, keep having fun!

Further reading:

FAQs About BMX BB Types

What are the main types of BMX bottom brackets?

The main types of BMX bottom brackets are American BB, Mid BB, Euro BB, and Spanish BB. Each type has its unique design and compatibility features.

How do I know which bottom bracket type fits my BMX?

To determine your BMX’s right bottom bracket type, check your bike frame’s specifications or consult the manufacturer. The frame design and crankset compatibility often determine the bottom bracket type.

Can I switch from one bottom bracket type to another?

Switching between certain bottom bracket types may be possible with the right adapters, but I don’t recommend it. Sticking to the bottom bracket type designed for your frame is best.

Why does the weight of a bottom bracket matter?

A bottom bracket’s weight can influence your BMX bike’s overall weight. This then affects handling, performance, and ease of performing tricks. With a smaller BB, the frame needs smaller BB tubing, which together reduces weight.

How often should I service my BMX bottom bracket?

The frequency of bottom bracket servicing depends on your riding frequency, conditions, and the specific BB type. Generally, it’s a good idea to service your bottom bracket at least once a year or more often if you ride in wet, muddy, or dusty conditions regularly.

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About Author

Rok has been riding BMX for 20+ years, and when he's not having a session, he binges on videos, new product drops and works on creating the best content (sharing tips, tricks & more to make riding bikes easier for you) for The BMX Dude.