Rattles and replacing stuff

supermurph09

My Canyon Ultimate SL 9 has covered over 9000 miles in all weathers and quite a few hours on the turbo, in short the bike is developing lots of annoying creaks and rattles so I’m looking to replace some of the parts.

Given that some noise comes from the BB area I figured that would be a good place to start, is it generally a given that after this many miles you should replace it anyway? At £28 plus installation I figured this would be a cheap starting point, the pedals are next on the agenda.

Also, the cassette is tight, there are no problem with the wheels but there is a definite rattling noise from the cassette area (90% sure it’s that far back), this disappears when I’m on my smallest cog of the cassette, in this case the 50/11. The nearer the chain is to the middle the more the rattling occurs. Any thoughts? It happened before I had a new bottom bracket cable guide installed so I have no reason to think it’s related to that. The chain is less than 12 months old.

Really appreciate input.