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Tutorial: How to remove a one piece bottom bracket

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While fiddling with the screw in seat post bike I decided to keep the one piece bottom bracket. Those are common on kids bike but I’ve also seen them on cheaper/older bikes too. Those must be the easiest bottom bracket to remove in my opinion.

You need:
– flat head screw driver
– big crescent wrench
– a rag

Tools for the job

Sometimes I use a morale helper. He’s nice he comes to visit and he lays down and stay quiet while I work.

Hank the helper

What does that look like?

Bottom bracket on the chainring side

First thing to do is to remove at least the left pedal as it won’t fit through the bottom bracket hole.

The side we work on

Now you will need the crescent wrench and make it fit to the first bolt. Unscrew it clockwise.

Crescent wrench at work

Unscrewed bolt

Next there’s going to be a washer. You can see it in the picture above.


Next is the last bolt. It had two slices in it. There’s a special tool for it but I never needed it so far. This bolt can’t be tight otherwise it would squish the bearing and the crank harms would be unable to move. Usually I’m successful by hand. If it’s a little tighter you can use your screw driver to help. This one goes clock wise too. One the bolt is starting to loosen the bottom bracket you might want to have your rag close by.

Last bolt

What it looks like on the other side.

After this there’s going to be a bearing crown which is usually loaded with grease. I’ve seen the inside rusted and seized but this is not usually the case. Unless the seat wasn’t on the bike and the bike have been left out for year then there’s chances that it will be rusted.In the picture bellow you can see a bearing crow well greased and that’s on this side that it’s going out.

Bottom Bracket hanging out

What it looks like inside

I like to have my pieces cleaned up before I store them.

Bottom bracket apart and cleaned

The chainring can be removed from the crank harms too. I like to clean my bearing crowns every time the bottom bracket get opened up. This way I can avoid particles to stick to it and I like having fresh grease.


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