My bike has developed a squeak that is irritating me. It squeaks when I shift, but not every time. I can't tell if it's coming from the front (the shift lever) or from the rear derailleur. I took it to my LBS last week to have it checked and they couldn't hear it (of course not, sweetheart, you have the radio blasting throughout the shop! ), but I hear it very clearly when I'm riding. Can anyone tell me where to start to figure out where the squeak is coming from and hopefully remedy it? I'm embarrassed to admit that I know more about how my car works than how this bike works, but that's going to change.

Thanks!

KB