Originally Posted by kid charlemagne

Hi,

I'm pretty new to cycling and just recently got my bike back from the LBS after its first tuneup. I have a 2004 Lemond Reno with a double chainring and a tiagra front derailleur and a 105 rear. I noticed that when I'm in the big ring and any of the 3 largest rear cogs, I get a faint buzzing/rattling from my chain, that is more noticeable during a portion of my crank's revolution, so it sounds like a cyclical zzzz...zzzz....zzzz whenever I pedal. I think it's my chain rubbing against my front derailleur, but I could be wrong. This only happens when I'm in the big ring and is more noticeable when I'm in the largest cog (I know, I shouldn't be in a big/big gear combo, but I did it just for troubleshooting purposes) and less noticeable as I go to the 2nd and third largest cog in the rear.

What are your thoughts to troubleshoot and fix this? I keep reading about 'trim' adjustments. Could a 'trim' adjustment be what I need? If so, what is this trim adjustment and how do I do it?

I don't want to go back to the LBS if it's a quick fix I could do at home.

thanks in advance!