External Bottom Bracket O-Ring?

[baggytrousers]

I am about to replace the external bottom bracket on my Giant Defy but when I removed the left crank arm there was a thin O-ring between the crank arm and the outer face of the bottom bracket shell - I assume this is to help keep out water however the new bottom bracket didn't come with a replacement nor is it mentioned in the fitting instructions - I've looked at the Shimano website and it's clearly shown on a picture of the crankset and there is an O-ring on each side part no. Y13F16000 - Any ideas if this is essential and where I could get two from?

 

[rusty bearing]

I believe you only get these with the chainset, most likely you'll get away without them if you can't re-use your old ones.

 

[corshamjim]

Would that be this one?
http://www.sjscycles.co.uk/shimano-...lowtech-ii-axle-ring-1f3-1600-each-prod24989/

Certainly SJSC seem to have quite a selection of BB spacers. I bought a simple one from them recently to fill the gap left when I removed a chainguard mount.

 

[betty swollocks]

I assume they're spacers so that you can get the chainline right?
So you may, or may not need it/them.
Can you not re-use the one you had?

 

[martint235]

When I bought a Hollowtech II compatible from Token, it came with two O rings but the website said these were to make it compatible with SRAM. I initially left them off but ended up putting the right hand one back on just to ease shifting on the front derailleur.