The past few weeks my bike would make the odd, squeaking noise, only when I pedal and it seems only in the top three sprockets. It was definately coming from the rear though.
So I had enough of it and figured that my chain needed a cleaning (lube didn't seem to make it go away).
I clean the chain, rear sprockets and chain rings I lube the chain. I spin the cranks, no squeaking so I figured probelm solved.
The next day I hea dout on a 90km ride and about 1/4 way into the ride, holy crap, the thing starts to squeak like crazy! Even when I shift there'd be this loud SQUEAK. It would squeak in the bottom 3 AND the top 3 sprockets. I discovered very quickly that only the middle 3 it wouldn't squeak. Jeez, it was loud, so I finish the ride only using the middle three gears.
I was pretty darn sure I lubed the chain enough the night before, so it couldn't be that.
Anyway, when I get back I put the bike on the stand spin the cracks, and sure enough there's that squeaking again. I listen for awhile and sure enough it's coming from the rear, doesn't sound like the chain, but I can't imagine what else it could be, as it not only squeaks when I spin the cranks but it also lets off this loud squeak when I shift. I grab a differant chain, install that one and yup, the squeaking is STILL there. I listen for awhile longer and I gently push my index finger against the top jockey wheel of the rear derailler and the squeaking stops. A HA!
I take off the chain, remove the jockey wheels and discover, much to my surprise, that the inside of the jockey wheel has a layer of fine rust on that cylindrical metal piece (don't know name) that sits between the to metal washers of the jockey wheel. Since this bike never sees rain I can't imagine how it started to rust. My touring bike is in the wet all the time and I have NEVER had this problem with that bike. In fact, I have never had this problem in all my years of riding.
I lube the jockey wheels, reinstall and presto, problem solved. Not much lube is needed, a little dab'll do ya.
I post this in case it ever happens to y'all and you can't seem to figure out where that squeaking is coming from.....check yer jockey wheels.
I am looking forward to quieter rides from now on.