How to Overhaul a Bottom Bracket
How to disassemble, re-grease, reassemble and adjust a cup and cone bottom bracket.
- 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.
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.
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.
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.
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.
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.
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!
- Park Tool Park HCW-11 Adjustable Cup Wrench
- Hozan C-205 Lockring Tool
- Super Lube White Grease Tube
- Finish Line Grease Gun
- Shimano TL-FC10 Crank Extractor
- Park Tool CCW-5 Crank Wrench
Discuss this topic in the Bottom Bracket Forums
I have a 1999 Trek 820 AL whose bottom bracket is dying. According to the spec sheet, it's a Shimano BB-CT92E, 68mm shell, 116mm spindle, English threading. What is the easiest way to identify a suitable replacement? I found a NOS BB-CT91 with the same measurements on eBay for $20, any reason not to pull the trigger on that? Thanks!...Read more
Good afternoon internet hive mind. A friend has inherited a bike that has a wobbly bit somewhere inside the bottom bracket. I'm taking bits from old bikes to cannibalise into a new one to make it rideable and to be honest the whole thing is a great learning experience for me anyway, but I've hit a problem. In the past I've removed the bottom bracket with the correct tools, then to remove the bit t...Read more
I'm new to bike repair and maintenance, and I'm using my Dahon Speed 7 as my guinea pig. So far I've managed to replace the rear wheel, remove the casette, replace the brake cable and adjust the derailleur. My next project is to remove and replace the bottom bracket. I understand I need some tools to do this, but I'm not sure which ones. So, can anyone tell me which of the following I need? ...Read more
When I ride in a fairly low gear, about the 4th or 5th easiest gear and am peddling pretty hard, I hear a knocking sound that sounds like the bottom bracket, difficult to tell though. When I ride harder in even lower gears, it doesn't knock. Very confusing. I've just had a major maintenance completed at a good shop but it still happens. Any ideas out there about what it could be? Thanks! Dan...Read more
Hi, I received my brand new BMX last week, and already on the next day after I assembled everything I noticed an annoying creaking noise and felt some kind of clicking of the cranks under load, for example if I ride uphill. I disassembled the whole bottom bracket, cleaned everything (althout everything was clean and greased already) and regreased it. Nothing changed. What should I do? Is this norm...Read more
I've read a bunch of tutorials (including the sticky here) and the only part i'm unsure of is how thoroughly one must clean out all the old grease before regreasing and reassembling. I've wiped everything down and it is reasonably clean. Wondering if that bit of grease stuck in the bearing ring will contaminate and ruin the new grease or if a bit of mixing doesn't matter and the cleaning step...Read more
Has anybody else ever worked with this? I have installed the bearings which went into the frame by hand and are straight, but whenever I get to tightening the cranks it seems to bind up and there is no way that I will be able to get to the recommended torque level of 48nm. The cranks have the correct order of wavy washer then seal on the drive side and just the seal on the non drive side. The amou...Read more
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Hi, My old cheap 2003 Huffy bike has this BB: Since I actually enjoy riding this cheap "beater", I plan to do some upgrades. I want to remove this BB and convert to a square taper BB (because I am now familiar with SqT BB's, having replaced two of them on other bikes), and I will install a new crankset compatible with the new SqT BB. -Can you help to identify this old Huffy BB? (Is this...Read more
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