Jim’s Tech Talk
By Jim Langley
Sometimes questions come in that are so open-ended, I don’t know how to reply. Like Rubin’s query in the title of this Tech Talk. The thing is that there are so many different types of bottom brackets that more information is needed to be able to provide the best answer.
Since I don’t have any information and because I couldn’t reach Rubin to ask, I’m going to answer more generally. Hopefully it will come in handy if you have the same question. Having worked for Praxis for the past six years, a crankset and bottom bracket manufacturer, I have some experience in removing bottom brackets.
What’s a Bottom Bracket?
In case you’re just getting familiar with bike terminology, the bottom bracket (often abbreviated as “BB”) is the bearing mechanism installed in the frame that the crankset is attached to and that makes pedaling possible.
Helpful resource: My Parts of a Bicycle chart is one of the most popular pages on my personal bicycle website. To see the bottom brackets, read the section below the chart: https://jimlangley.net/wrench/bicycleparts.html.
Why Would You Remove the BB?
A good quality bottom bracket can run trouble-free for several years without any service at all – sometimes much, much longer even. Bad quality BBs might not even last a year.
BBs that are excessively ridden in foul weather, subjected to river crossings, gravel, mud, snow, etc. usually will develop issues such as roughness or play (looseness) in the bearings. Because the grease inside the bearings can wear out. And, if enough grit builds up inside the BB and bearings, it can ruin it quickly.
And that’s where removal comes in, to replace the BB with a new one. Or because it has developed a problem you haven’t been able to fix, such as making creaking noises. Or maybe your BB just has worn-out bearings and you want to install new or different bearings.
Figuring Out What Type of BB You’ve Got
It’s best to remove the crankarms to identify your bottom bracket. It makes it much easier to take any measurements and to see the parts making up your BB. To remove the crankset, you’ll need the correct tools for your crank.
To determine what type of BB you have, I recommend reviewing Park Tool’s library of bottom bracket written and video information here (you’ll also find crank information):
https://www.parktool.com/blog/repair-help?query=&area%5B%5D=47
You Only Need to Know About Your BB
Don’t panic when you start learning about BBs. You only need to master your BB. You don’t need to become an expert on the many different types – and there’s been a crazy number of them added of late.
Just go through the guides looking for a match with what’s on your bike. When you find it you’ll then be able to learn about the procedure for removing your type of bottom bracket along with the recommended tools. Once you’ve learned about your setup and removed it, you’ll see that the job’s not overly difficult with the right tools and procedure.
If you dig into it a little and your head spins, no worries. In that case, just head to your local bike shop for professional help. A little more about this in my next to last paragraph.
Tools
As I mentioned, you’ll need the correct tools to remove your crankset in order to access the bottom bracket. Besides for BB removal, It’s nice to own these tools in case you ever have to remove the crank to replace a worn out chainring or if the crank ever needs tightening.
For BB tools, there are many types to go with the many different BB designs. To simplify it a lot, the three broad categories are BBs with threaded cups, press-in cups (also known as press-fit cups) and press-in bearings.
For threaded cup BBs, you get the tools, either wrenches or oversize sockets that fit the cups and let you turn them to unscrew the cups from the frame. You must get the correct wrenches for your specific BB.
The two examples shown may not be the correct choice for your bike. They’re just to show the two types of tools for threaded cups.
Here’s Park’s BBT-29 Wrench:
https://www.parktool.com/product/bottom-bracket-tool-bbt-29?category=Crank%20%26%20Bottom%20Bracket
And, here’s the latest threaded cup socket tool from Park Tool:
Park BBT-47-12 Socket
For press-in cups and press-in bearings, you get the tools needed to knock the cups out of the frame. Or for press-in bearings, to knock them out. These jobs usually involve one or two of these three Park tools – or similar design tools:
Park BBT-30.4 BB Tool Set
Park BBT-90.3 Press-Fit BB Tool Set
Park RT-1 Headset and BB Cup Remover
https://www.parktool.com/product/head-cup-remover-rt-1?category=Crank%20%26%20Bottom%20Bracket
For getting press-in bearings out of frames, you may also need a tool for removing the snap rings often used inside frames to keep the bearings in place.
Removal Procedure Basics
Bottom brackets with threaded cups are usually easy to remove with good tools. Just remember that the drive-side (right hand cup) can be reverse threaded. Most modern threaded BBs are this way. This means turning the cup to the right to loosen it.
The left cup (non-drive) is turned to the left to loosen and remove it.
Note that if you work on older European bikes, such as from before the mid 1980s, you can run into right cups that are regular/standard threaded on some frames. Those are turned to the right to tighten and to the left to loosen.
Bottom brackets with press-in cups and press-in bearings can come out easily or not. It depends on how tight a fit the parts are. Sometimes they’re not tight at all and can be pulled out by hand. Press-in bearings are more likely to come out easy than cups but be sure to look for and remove any snap rings holding them in position first.
Press-in cups can be very tight in the frame. It can help to have another person brace the bike as you use the tools and a good hammer to strike the tool and knock the cups out of the frame.
You’ll want to read up on the bottom bracket brand and model you’re trying to remove to be sure you’re following the correct steps and using the tools they recommend, too.
Focus to Avoid Damage to Yourself and the Bike
When you’re knocking bottom brackets out of frames, pay close attention to what the tool is resting against inside the frame. You don’t want to damage the frame, which could happen if the tool was against the carbon instead of against the cup or bearing.
Use a flashlight if needed to look inside and make sure you’re hitting the correct thing. Here again, having a helper can make the job go more smoothly and avoid serious mistakes. Your assistant can also prevent the cup from shooting out of the frame and hitting something or getting lost when it finally comes free.
One more thing. Be careful swinging the hammer. Don’t hit your hand holding the tool or the frame!
Good luck!
I know these are only general tips for BB removal, but I hope they’ll help you learn enough to handle the job. I wouldn’t call it easy but with the right tools and working carefully it’s not that difficult for most types of BBs. And it can be highly satisfying to replace a problem BB yourself.
Keep in mind that if it all seems too complicated, you could have your local bike shop do the job for a lot less than the cost of the tools alone. They will be happy to install the new BB, which also requires dedicated tools.
Your Turn
If you have tips and tricks for removing bottom brackets and/or favorite tools you recommend for Rubin and others, please share them in a comment. Thanks!
10,186 Daily Rides in a Row
Jim Langley is RBR’s Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his “cycling aficionado” website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim’s cycling streak ended in February 2022 with a total of 10,269 consecutive daily rides (28 years, 1 month and 11 days of never missing a ride). Click to read Jim’s full bio.
Let’s go back to the definition of what a BB is. I think a better way to describe it is “a bicycle component system used to connect a bicycle’s crankset to its frame, allowing the crankset and ultimately the pedals to rotate independently of the frame itself. The BB system is usually comprised of a set of bearings, cups that house the bearings, shims, spacers, and/or washers.” The 3 main types of BB’s are denoted by their retention system, i.e., threaded cups, press-fit cups and direct fit where the frame is the cup.”
Agreed, it is usually the bearings that go bad. Premature bearing wear can be attributed to (1) garbage quality parts, (2) riding in adverse environments where water, sweat, dirt, debris can enter the bearing internals, (3) misalignment of the ‘BB’ holes in the frame where the crank spindle places an extremely high load force on the bearings causing accelerated and premature wear (see hambini for more analysis).
Hope this helps
Unior makes a nice tool for getting BB90 bottom brackets out without all that hammering. https://uniorusa.com/collections/crank-and-bottom-bracket/products/tool-for-removing-bottom-bracket-bb90
Thanks a lot, Jeff. Unior keeps coming out with nice tools. And it looks like a clever mechanic could make their own version without too much trouble.
Appreciate it!
Jim