Adjustable Bottom Bracket Service

Today I regreased the bottom bracket on my 40 year old Dawes Lightning. It was probably the nastiest looking bearing I've ever seen, with lots of dirt and dried up grease all over the bottom bracket shell. I took some pics too so I'll show you how to service the old style bottom brackets in this little tutorial.

First you need to remove the cranks. This bike uses cotter pins, so you can read my earlier post on cottered cranks if yours are like this one. If you have square tapered cranks you just remove the crank bolts and then use a crank removal tool to slide the crank off the tapered spindle. Also if you're replacing your cottered cranks with square tapered ones you won't have to replace the entire bottom bracket, just the spindle.

 

With both cranks removed it's time to take the bottom bracket apart. First remove the lockring on the adjustable cup. This will be on the non-drive side. I used a little tool with an adjustable pin on the end of it, but there are also bike specific lockring tools available. If you're working on a beater bike then you can just use a vice grip or a hammer and punch if you don't want to buy a proper tool.

 

Here is the lockring removed. The next step is to unscrew the adjustable cup. These usually have wrench flats where you can put an adjustable wrench on, this particular one just has little holes to put a pin spanner on:

Once the cup is off you can slide the spindle out. Keep track of any ball bearings that will inevitably fall out.

The last step to disassembly is sort of optional. You will need a big wrench to remove the right side cup. This is also called the "fixed" cup since it is screwed tightly into the frame and can be difficult to remove. If you choose to leave it in it will be much more difficult to clean the bearing surfaces, which is why it's "sort of" optional. Anyway you remove it with a big wrench on the two flat sides of the cup:

Now if you have an Italian or old French frame you will just unscrew the right side cup normally (counterclockwise). If you have anything else (British, Japanese, American, etc.) you will actually have to turn it clockwise because it will be reverse threaded (just like a left side pedal). If the cup is hopelessly seized in the frame due to rust then you might have to stick the cup in a bench vise and use the entire frame as leverage to unscrew it. Fortunately I didn't have this problem so here's the empty bottom bracket shell:

Clean every bearing piece as best as you can:

Now grease the cups and stick the ball bearings in. Having a nice thick grease will keep everything in place. If you have bearing retainers make sure you put them in the correct way, usually with the smooth side facing the cup and the jagged side facing upwards.

Now clean the threads inside the bottom bracket shell and add some grease to them before screwing the cups back in. Screw the fixed cup all the way in first, but don't tighten it just yet. If your wench slips you could knock the balls out of place so I like to wait until the adjustable cup and spindle are installed.

Pay attention to which direction the spindle goes in. It will usually be longer on the right side to make room for the chainrings. Anyway once the bearings are loosely installed you can torque down the fixed cup. I don't think you can overtorque it with normal hand tools so just make it as tight as you reasonably can, and be careful to not get hurt if your wrench slips.

Now it's time to adjust the bearings. Screw the adjustable cup in until the play in the spindle disappears. Then you can install the lockring.

After tightening down the lockring check for any play in the spindle. If there's play then you have to loosen the lockring, screw the left side cup in a bit more, then tighten the lock ring. It's sort of a trial and error process. Sometimes the bearings will loosen a bit by themselves from the force of the lockring, so you might have to overtighten them at first to compensate. I like to overtighten them just a little bit anyway since these adjustable bottom brackets tend to loosen up a little during use. If the bearings have no play and don't bind up as you turn the spindle you can consider it done. Just reinstall the cranks and enjoy your freshly greased bottom bracket.