well, i'm sure where to start so... yesterday i was riding to class and my chain loosened up a lot for some unknown reason. i attributed it to the QR, even though i haven't ever had any problems with it, and just loosened the back wheel, made sure it was all the way back in the dropouts, and that was that.

the tension was fine today, but then my drivetrain started making a squeaking noise that i can't figure out. i recently degreased and lubed my chain, so i thought that maybe i hadn't lubed it enough. after putting more lube on it, and letting it sit for a couple hours, it's still squeaking. it's hard to pin-point the origin, but it sounds like it might be coming from the back wheel. can anyone help me with any ideas of what it could be? my hubs have sealed bearings, but could they be messed up? that's the only reason for the problem that i can think of at the moment. any help would be appreciated.

Try checking your chainring bolts. If you ride clipless check your cleats on your shoes.

check for mice in the BB.

Check you seat. Could sound like it's coming from the drivetrain but it's really sitting right there under your ass!

You could have tightened your chain too tight. Is it pretty stiff when you spin it around? Maybe try putting just a little bit more slack in the chain and see if you are still getting the noise. This has happened to me.

it's definitely not the seat, i put my bike on the seat and checked just to be sure. thanks for the other suggestions. the chain is as tight as it's always been, so i don't think there would be a problem with that. i do need to tighten the chainring bolts, so hopefully that will be the solution. now it's just a matter of acquiring the tools, since i don't have anything with me at school...

so i tightened the chainring bolts, and the sound is still there. i'm beginning to think that it's the BB, but i don't know. :-\

try the bottom bracket. i've learned to recognize a particular squeak that only responds to disassembly, cleaning of threads, and reassembly (well, plus loctite since i have one of those wandering italian right-hand thread drive side jobs).

i'm not that profiecient in bike mechanics, and don't know anything about bottom brackets. i don't want to make the problem worse by riding on it; so i guess i'll keep walking, and get it looked at when i have the chance.

Jesse, flip the bike over and turn crank slowly while your ear is close to the chain/cog...do you hear a squeak? Then do same thing, only at chainring end...do you hear it then? I've noticed on mine that when I have chain just a tad too tight I'll get the squeaking. I'd rule that out before worrying about BB - when it gets close to being toast you'll have noticable roughness/resistance and prob some side-to-side play as well.

How long have you been using the chain?
your chain might be too stretched.
bring it to LBS and let them check the stretch.
I have to change my chain pretty soon as well.

i should have been more specific - i was talking about the creaking that happens between the cups and the shell, as opposed to the squeaking between dry bearings and races. the former is really only a nuisance, whereas the latter is the sound of damage taking place and needs correcting.

jesse - the sound i'm talking about would only happen when you actually rise the bike, putting pressure on the pedals/cranks. if you can get the sound with the bike flipped over as dabern describes then it's not what i'm talking about. sounds like a job for the lbs - they can actually see and hear your bike, we can only imagine it...

thanks for all of the help, guys. i'll definitely have the lbs check it out for me.

i had a mysterious creak yesterday, turned out to be my pedals (i think)
i had just went from a 38t to a 44, i guess the increase in the force required translated to too much stress on these cheap-O Wellgos (borrowed from my mountain bike until I get some good ones for the fg)