Odd sized BB fixed cup

Tenorman

Active Member
Location
Newark-on-Trent
Whilst trying to replace the old cup and cone BB with a cartridge on my other half's hybrid, I've been faced with a fixed cup that is seized quite badly. Normally I've been able to get away with using a large adjustable spanner for these things, but I can't get a good enough grip, so considered buying a proper closed cup spanner (even though I won't need it after replacing with a cartridge unit). Anyway, the fixed cup has a size of 34.8mm on it. Surely these are normally 36mm, and that's what all the spanners are. Has anyone come across a 34.8mm BB fixed cup before, and where can I get a spanner to get it off? Or - am I being particularly dozy and have missed something silly?

Cheers
 

TheDoctor

Europe Endless
Moderator
Location
Stevenage
This sounds like an LBS job to me.
Normally I wouldn't suggest it, but it might be easier (and cheaper!!) than trying to find an oddball tool you'll only need the once...
 
OP
T

Tenorman

Active Member
Location
Newark-on-Trent
This sounds like an LBS job to me.
Normally I wouldn't suggest it, but it might be easier (and cheaper!!) than trying to find an oddball tool you'll only need the once...

I think I'd agree with that. I have actually found a reference though that "British" BB threads are 34.8 mm (or 1.37 inch), so maybe it's referring to the thread rather than the spanner required. My tape measuring isn't that accurate, and I don't have calipers. Maybe a standard 36mm spanner would fit - but then again I'd only need it once so will probably take the bike to my LBS.

Thanks
 

tyred

Legendary Member
Location
Ireland
Get a 5/8" bolt and some 5/8" spring washers and put the bolt through the centre of the BB with the washers on the inside and tighten it, keep tightening it until it grips the cup and unscrews it. This works as it's a left hand thread. You will need a large slim walled socket to reach through the BB shell but this method won't fail but it can be very tight. Tools used need to be of good quality and a helper can be useful to hold the bike. There is a more detailed explanation of this on Sheldon's site if you look.
 
OP
T

Tenorman

Active Member
Location
Newark-on-Trent
Get a 5/8" bolt and some 5/8" spring washers and put the bolt through the centre of the BB with the washers on the inside and tighten it, keep tightening it until it grips the cup and unscrews it. This works as it's a left hand thread. You will need a large slim walled socket to reach through the BB shell but this method won't fail but it can be very tight. Tools used need to be of good quality and a helper can be useful to hold the bike. There is a more detailed explanation of this on Sheldon's site if you look.
Ah, I can see how that would work. But, in the end I took it to the LBS. It's still having the BB soaked with various penetrating fluids - really seized! I guess that I wouldn't have been able to get it off anyway.

Cheers
 
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