Bottom Bracket

[RecordAceFromNew]

RAF thankyou yes it does clarify.

I have measured the chainline and its 50mm. I did use the 118 x 68 BB as recommended. Would it be worth fitting a 113 x 68 thereby reducing the chainline to 45?

I might have misunderstood what you are saying Obelix, but I am somewhat concerned having read what you wrote. It is clear from Shimano's spec I linked to above that the FC-5500 triple chainset should have a 45mm chainline with their BB-5500 bottom bracket. Since it is not a square-tapered system there should be little if any if's and but's about the precision of the chainline delivered - i.e. it is unlikely to end up being 50mm.

I wonder if you could check whether you have the right bottom bracket. In particular the BB-5500 is an Octalink V1 bottom bracket, and should not be confused with the far more common Octalink V2 bottom brackets, the important issue here is that force fitting one version on to the other will inevitably ruin the chainset. I hope you have not been sold the wrong version, but if you were you must check the crank and be sure the steel bottom bracket spindle has not chewed up the soft alloy fins of the chainset - if it did I am afraid using the chainset will be hazardous and it has to be binned.

You can read about the difference of those bb's here.