Bottom brackets standards can be difficult to identify.
In this video we are going over how to identify what bottom bracket standard is on your bike.
Calvin Jones here. - Truman here, with Park Tool Company.
We're going to go over different bottom bracket styles
and then send you to the appropriate video to work on that system.
All of these videos can be found in our bottom bracket playlist -
found at any point here by hitting the information icon in the corner.
The bottom bracket is the bearing system between your bicycle's cranks.
It sits inside the part of the frame called the bottom bracket shell.
The bearings of the bottom bracket are typically held in the bottom bracket shell by an adapter or a cup.
The spindle of the crankset passes through the bottom bracket bearings and is connected to your bicycle's crankarms.
Depending on your crank and bottom bracket type, this connection may look different.
Before watching this video, we recommend reading the repair help article on parktool.com on Bottom Bracket Standards and Terminology.
This article will help you gain a basic understanding of the different bottom bracket shell types
and the bottom brackets that can be installed into them.
Crank removal is the first step of bottom bracket identification.
See our crank playlist for removal procedures.
Once you have the crankset removed, you will be able to see more of what is going on.
If during crank removal, you discover you have a one-piece crank,
the process for crank removal and installation also includes bottom bracket removal and installation,
so see our one-piece crank video for the complete process.
The same is true for Campagnolo Ultra Torque systems.
The bearings are installed on the crankarms,
and the process for their removal and installation is covered in the appropriate crank video.
Let's have a look at the remaining styles and their identifiers.
One of the first things to look for is tool fittings.
A tool fitting can be external notches,
internal notches, internal splines,
pin holes, or wrench flats.
First, let's look at the cup & cone-style bottom brackets, which are an older design.
Cup & cone-style bottom brackets feature two tool fittings on the non-drive side,
one of which is an outer lockring, and the second one is an adjustable cup.
One exception this this Shimano Ultegra Octalink BB5500.
The bottom bracket has both internal and external tool fittings.
It is a threaded cartridge bottom bracket, which we will address later in this video.
See this video for cup and cone bottom bracket service.
In this example, we notice that there are no tool fittings on the outside or the inside.
This is a press fit bottom bracket.
They are installed into non-threaded bottom bracket shells by pressing.
See this video for installing and removing press fit bottom brackets.
The remaining bottom brackets we will look at all feature tool fittings and some sort of threading —
either on the bottom bracket itself,
or inside the bottom bracket shell. Lets take a look.
A thread together bottom bracket, also called thread-thru,
is similar to a press fit in that it installs into a non-threaded shell.
However, the right and left cup have tool fittings and thread together inside the shell.
It can be confusing to differentiate these from some bottom brackets that install into threaded shells, which are visually similar.
Threaded shell bottom brackets are also installed using tool fittings -
these bottom brackets have threading on the cups, which is threaded directly into the threaded bottom bracket shell.
It can sometimes be difficult to distinguish these two types from each other,
and it is possible to damage your frame or components if you guess incorrectly.
If that makes you uncomfortable, consult the professionals at your local bike shop for guidance.
Although from the outside, both systems look the same, there are some indicators that let you know it is one or the other.
Let's look at some examples.
On this bike, we see tool fittings, so we know it's either thread-together or a threaded shell.
Inspect inside the shell, and we find threads exposed only on one side, which you would not find in a threaded shell bottom bracket.
This is a thread-together.
On this bike, we also have tool fittings.
But we see T47 printed into the cup,
which, as we know from reading the bottom bracket standards article at parktool.com, is a threaded shell standard.
This bottom bracket is installed in a threaded shell.
On this bike, it's not immediately clear.
In some cases, to be 100% certain, it may be necessary to remove the cup and inspect inside the frame.
For this you need the correct tool.
See this article at Parktool.com for help with tool selection.
In this example, this tool fitting has 16 splines and a nominal outside diameter of 44 mm.
Generally remove the left cup — the non-drive side.
We do this because both threaded shell-type and thread together type bottom brackets loosen counterclockwise on the non-drive side.
Thread-together bottom bracket cups are right-hand thread for both sides.
However, if the bottom bracket has a full collet, such as this Praxis option, it is left in place while the opposite side is removed.
Inspect both sides for a "DO NOT REMOVE" label. Remove the opposite side counter clockwise and inspect the frame.
Inspect inside the shell of the frame.
If the frame shell is smooth on the inside, it is a press fit shell.
The bottom bracket is a thread-together style bottom bracket, which has its own video here.
If the frame shell is threaded, your bottom bracket is likely one of these threaded styles.
It may be a cartridge bottom bracket.
Cartridge bottom brackets feature a spindle integrated into the bearings as a self-contained unit.
See this video for for threaded bottom bracket removal & installation.
Threaded thru-spindle bottom brackets are comprised of a cup with a cartridge bearing.
These bottom brackets are threaded into the frame, and then the crank spindle passes through the bearings.
See this video for for threaded bottom bracket removal & installation.
This concludes our bottom bracket identification video.
Remember, there are always new standards and new tool fittings coming out.
You may need to contact your manufacturer or visit your local bike shop for more information.
We hope we've helped you out on your bottom bracket journey.
If we've helped you out, be sure to like and subscribe.
And if you have any questions, leave them in the comments section.
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