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Parts and tools for changing a bottom bracket
#1
How difficult is it, and what tools are needed, to change out a bottom bracket?
Dave

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#2
Hi Dave,
There are 3 common bottom brackets shown here:<br />
http://www.sheldonbrown.com/gloss_bo-z.html#bottom
Which one do you have?

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#3
I have to go look at the bike when I get home. It's a fairly new specialized tarmac, and suspect it is the cartridge type set up. I sure appreciate your assistance!
Dave

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#4
To remove your crank arms you'll need this tool:<br />
http://harriscyclery.net/itemdetails.cfm?ID=542
To remove the bottom bracket you'll need this:<br />
http://harriscyclery.net/itemdetails.cfm?ID=518
Once removed, you'll have to replace the entire bottom bracket. Unlike traditional bearing/cup units, the cartridge BBs are sealed, and meant to be replaced rather than serviced. Any good bike shop can match up your old BB and sell you a replacement. I'm hoping to do a video tutorial on this soon. Let me know how it works out for you.

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#5
Thank you! What a great resource!
Dave

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#6
Hi Alex. I'm replacing a sealed bottom bracket also. Do you know what the torque specs would be on a Shimano UN54? There's nothing in the box telling me how tight to install it.

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#7
Tighten it with about 360 inch pounds, which equates to 30 foot pounds, or 40 Newton Meters (Nm).

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#8
Thanks Alex. Both sides? The left side is a plastic piece.

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#9
Sorry... yes only the metal end. The plastic side just needs to be snug.

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#10
Excellent. Thanks very much.

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#11
Hi there

Can I revive this thread please - apols!

I ask, as there appears to be two different tools required to remove both cups of a standard Shimano cartridge bottom bracket....

I've just picked up an old Orange Prestige which I'm about to restore, and I was able to remove the non-drive side (I believe the bb had been installed back to front) using a Shimano UN74 tool and a 32mm spanner. However, there is a plastic cup left in the bb in the drive side, and the same UN74 tool is too big to fit into the splines on this cup - what model of Shimano tool do I need to remove the cup that remains?

It was a cheapo CS-21 sealed cart bottom bracket for identification.
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#12
It should be the same tool for each side.

Am I correct that you've removed the cartridge and now just have the old plastic cup stuck in the frame?

As it's a plastic part, you coould probably cut it and break it to get it out.
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