How to Overhaul a Bottom Bracket

Most bikes these days have cartridge-style bottom brackets which can't be overhauled or adjusted - so if they develop play or stop turning smoothly, it signals that they may be damaged or worn out. Below are instructions for the cup and cone style bottom brackets found on most bikes built before the mid-1990s.

Instructions

1. Assemble the proper tools. You will most likely need a pin spanner and a lockring spanner. If you are unsure, check with your local bike shop.

2. Place your bike in a bike stand. An overhaul can be made without a stand, but a stand makes it much easier.

3. Remove the cranks. See "How to Remove Bike Cranks."

4. Go to the left side (or non-drive side) of the bike. Place the lockring spanner on the lockring. Be sure they are a good match and a snug fit.

5. Loosen the lockring. This may take a bit of effort. Be sure you think about it a bit before putting all your weight into it and skinning a knuckle (or worse). If there is corrosion, you may need to spray the threads with a penetrating lubricant and let it sit for a while first.

6. Fit the pin spanner in the slots or holes of the adjustable cup. Unthread the adjustable cup and remove it, along with the bearings on that side.

7. Pull the spindle out of the bottom bracket and remove the bearings that sit against the drive-side (also called "fixed") cup. The drive-side cup will remain on the bike.

8. Clean out both cups with a clean rag and inspect the bearing surfaces. If they are deeply pitted, you may want to consider a new bottom bracket.

9. Clean off the bottom bracket spindle and inspect the bearing races. Again, if they are deeply pitted, you may want to consider a new bottom bracket.

10. Clean the bearings in a jar with solvent. You might want to replace them with new ones.

11. Grease the cups and fit the bearings back into the both cups. Make sure you put as many bearings in as you took out. Smear some more grease on top of the bearings.

12. Slide the spindle back into the bottom bracket.

13. Thread on adjustable cup.

14. Thread on the lockring.

15. Adjust the bottom bracket. See "How to Adjust a Bottom Bracket."