Bottom bracket replacement

Broadside

Guru
Location
Fleet, Hants
I've just bought a second hand bike for one of my kids and need to replace the bottom bracket. It is an old style cup and cone type, can I simply replace this with a sealed unit like a Shimano UN55?

The bottom bracket shell measures 68mm which I think makes it English thread? The spindle/axle measures 115mm. There is a plastic white liner inside the bottom bracket at the moment, am I right in thinking I can just whip this out to make space for the new bottom bracket?
 

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Tim Hall

Guest
Location
Crawley
Yes, replace it with a UN55.
Yes, most likely English thread.
Yes, whip out the plastic liner.
 
OP
Broadside

Broadside

Guru
Location
Fleet, Hants
The only drawback may be removing the fixed cup. They can be very stubborn indeed. Sheldon has a DIY tool for doing this. http://www.sheldonbrown.com/tooltips/bbcups.html

Edit. Oh, it looks from your pics like you've managed to get it out, I think.
I'll get the rest out tomorrow, but I didn't want to remove the White liner until I had checked here first! It looks like it won't go back in easily.
 

Gravity Aided

Legendary Member
Location
Land of Lincoln
Good luck! Going through that myself. I'm also looking at the Sunlite BBs, Both have metal cups on both ends, so great durability. The only thing I've ever seen go wrong on a sealed BB was the plastic cup.
 
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