Bottom Bracket - British or Italian?

[Craig-SR]

I am upgrading my road bike to Shimano Tiagra and I need a 4600 bottom bracket for the chainset.

The problem i have is that i have seen a 68mm British Thread or 70mm Italian Thread. The tech docs for the chainset do not say which one to get.

Does anyone know what is the difference?

 

[smokeysmoo]

Chances are it'll be British but what's the bike?

 

[Craig-SR]

Its a Giant Defy 2010 model.

 

[smokeysmoo]

British

 

[Craig-SR]

British

Thanks for the quick reply. Is there that much of a difference?

 

[RhythMick]

Thanks for the quick reply. Is there that much of a difference?

I think the difference is in the left side thread. Both are left hand threads on the right side of the bike, but British is right hand threads on the left, where Italian are left on the left. With Italian, the left side is I guess more likely to loosen itself as you pedal.

That's probably as clear as mud, and I'm only recalling from reading about it I've never used an Italian thread.

 

[smokeysmoo]

Thanks for the quick reply. Is there that much of a difference?

2mm