I bought my bike 2nd hand about a year ago. It came pretty nicely set up with an Ultegra 9speed RD/Double FD, Dura Ace 7700 crankset.
I'm not sure how many miles I've put into it, but lately the drivetrain had started to sound bad and shifted poorly. When I say the drivetrain "sounded bad" I mean it's not as quiet as it used to be, and when pedalling in most gears, it sounds like I'm running a dry chain when it's lubed.
I bought a new SRAM 9-speed chain the other day, cleaned up some of the gunk on the cogs and chainrings and pulleys on the RD, installed the new chain, and the sound has only marginally improved. Now I have the problem of my bike wanting to shift on its own to a smaller (sized) cog. I tried to adjust the trim but it doesn't seem to help much. And when I backpedal (say when I'm doing maintenance), the chain sounds like it's going to skip, but there doesn't seem to be any stiff links.
I don't know how old the cassette is... do you think it's time to get a new one?
Finally, to top it all off, I'm starting to get this heinous creaking noise whenever I apply heavier force to the pedals (e.g. sprinting/climbing both in and out of the saddle). I checked all the chainring bolts, pedals, handlebars, and there doesn't seem to be any play in the cranks to suggest a loose BB. I'm totally stumped.