How To Overhaul A Bottom Bracket
How to disassemble, re-grease, reassemble and adjust a cup and cone bottom bracket.
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- 02:22 - IMPORTANT: Apply a thin layer of grease to the threads before inserting into the frame.
Today we’ll learn how to overhaul and re-grease an adjustable bottom bracket. To remove the cranks you’ll need a crank puller, a 17mm open end wrench and a large adjustable wrench. To overhaul the bottom bracket you’ll need a bottom bracket wrench or a pin spanner, a hooked lock ring wrench, and a 36mm wrench. For re-greasing the bearings you’ll need some cleaning solvent and waterproof grease, a rag, a toothbrush and a small container to clean the bearing cages.
Disassemble
Begin by removing the cranks. Watch the cotterless crank removal tutorial for a more detailed procedure. Once the cranks are removed, loosen and remove the lock ring on the non-drive or left side of the bike by turning counter-clockwise. Once the lockring is removed you should be able to easily loosen and un-thread the bearing race using either a pin spanner or a bottom bracket wrench.
Now pull the spindle and both bearing cages out of the frame. It’s important to remember which way the spindle came out, as they are directional. The drive side usually has a longer distance from the bearing race to the end of the threads. Wipe off the bearing cages, drop them into the solvent, and let them soak while you use your rag to clean the spindle and both outer bearing races.
Tighten the drive-side bearing race by turning it counter-clockwise with your 36mm wrench. Unless you are replacing the bottom bracket, there is no need to remove it.
Inspect
Shine a flashlight into your bottom bracket shell to inspect the bearing race for pitting and wear. Inspect your other bearing race and then carefully inspect the spindle. Most wear occurs on the spindle’s bearing races. If you see pitting here you should take it to your local bike shop for a replacement.
Clean
Now clean both bearing cages with a toothbrush and solvent, and then set them aside to air-dry. These should also be replaced if they are worn or have bent cages.
Grease
Apply a layer of grease on both bearing races and cages. A grease gun makes it easy to squirt grease inside the gaps between the bearings. Then place the bearing cages into both races. The rounded side of the cage should be facing down into the bearing race. Seal them in with another layer of grease.
Reassemble
Now insert the spindle the same way you removed it. Wipe off any excess grease that comes out on the spindle. Grease the threads inside the bottom bracket shell, and then slide the outer race and bearing cage onto the spindle. Thread it on all the way clockwise but don’t tighten it. Again you’ll need to wipe off excess grease.
Adjust
Thread on the lock ring finger-tight. Before adjusting the bottom bracket, first install the drive-side crank arm and tighten it as shown in the crank installation tutorial. This will help us make a proper adjustment. Now hold the inner race firmly with your wrench or spanner and tighten the lock ring. When properly adjusted the spindle should spin smoothly. If it doesn’t, you’ll have to loosen the lock ring, back off the inner race a little bit, and then tighten it again.
Check for play by placing the crank arm close the frame and pushing and pulling it against the frame. There should be no movement. If it feels loose, you’ll have to loosen the lock ring, tighten the inner race a little bit, and then tighten the lock ring again. When the adjustment is correct, install and tighten the left crank arm and you’re done!
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19 Responses to “How To Overhaul A Bottom Bracket”
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Hi Alex,
As all ways your videos are excellent, I would all so recommend before people put there bottom bracket back together they should put some Anti- Seize over the threads.
This will help to prevent both seizing due to corrosion of metal parts and stripping of threads.
Anti-Seize By Park tool web site: http://www.parktool.com/products/detail.asp?cat=82&item=ASC-1
Regards Anthony
Great site. Very useful. I always find cycle maintenance difficult, even though I spend many hours cycling.
Great tutorial as always!
This would have been a great visual aide when re-assembling mine… but Sheldon Brown’s (RIP) written instructions were just awesome too.
This is the only major repair I have ever had to make on any of my long distance bicycle tours. If you know how to make this repair, you can fix just about anything on your bike!
But my questions is, how do you make this type of repair when you are out on the road? While touring, I;ve always had to get my bike to a shop so they could make the repair for me because I wasn’t carrying the necessary tools.
Any ideas for making such repairs on a long distance bicycle tour?
Status of this Request
I have a question. I am restoring and old mountain bike which has a similar bottom bracket system. The bottom bracket needs replacement but I don’t know which manufacturers make such brackets.
I found one called Axix on some online store but I want to check a few more brackets. Could you tell any brands.
Thank you.
For this type of bottom bracket, there are many different styles and spindle lengths. I’d recommend taking it to your local bike shop for the replacement parts.
Once crank is installed should the distance from crank arm to the center of frame be the same on both sides? Thanks Al
Yup, the distance should be equal on both sides!
Wow that was fast. The reason I asked is I had a new set of cranks and BB installed by LBS and the left side is 2 9/16 ” and right side is 2 1/8″. The new cranks are the XTR M970’s. Can this be corrected with these cranks? Thanks. Al
A small difference like you’ve described is acceptable. The main problem with too much of a difference is that one leg would be further out than the other, so I think you’ll be ok with only 7/16″.
Hello,
I need a wrench to remove the bearing race. Can you tell me what the Park model number is for the wrench you used in the video? Thank You.
Finally found the tool you were using. Not sure but it may have been discontinued at some point and it was brought back.
Park Tool HCW-11 Adjustable Cup Wrench
Thanks elmonica… where did you find the tool?
Alex.
ebikespot.com had it for $11.45. I ended up using a pair of vise-grip pliers to remove it. I wasn’t worried about ruining it since I was intending to upgrade to a newer variety of BB. It turned quite easily so I can see how maybe one of those spanner tools might work as well. For the side with the lockring,my 30/32 headset wrench fit perfectly - I was surprised I actually had a tool that fit !
I used your other video for installing my new type of bottom bracket. Not sure I picked the right size bottom bracket for the type of crank arms I ordered (Bulletproof model). In process of attempting to learn what chainline considerations I need to take into account from Sheldon Brown’s website.
Great video ! very informative. Thank You.
Le
Hey, I’m a bicycle assembler for a national corporation. Where do you get the training to become a bicycle mechanic. I can build and repair and tune but not as well as I think I can. Thanks
Hi Dave,
The quickest way to learn would be to get a full-time job at a bike shop. If that is not a possibility, there are schools like the United Bicycle Institute.
I have the same type of bottom bracket. Some says that’s an old type. Can I replace it with a new one: Truvativ Powerspline? Will it fit?
It may work. You’ll have to get a new bottom bracket that matches the thread size and spindle length of your old one. It can be tricky so I recommend taking your old one to a bike shop to size up a new one. Keep in mind the Truvativ bottom bracket uses a special splined crankset.
Sheldon Brown has a great database sizing page that may help:
http://www.sheldonbrown.com/bbsize.html