I recently took a 7 day trip where my bike got rained on 5 nights in a row. My bottom bracket then developed a noise when I pedal. It isn't loud, and doesn't seem to affect my pedaling at all. It sounds like a little sand is in there....but there is no way sand could have gotten in. A friend told me it could be the bearings going bad...
Is this what it likely is? Is this an issue? Will it be ok for me to ride another 300 miles without taking it apart and fixing whatever is wrong?

have you tried cleaning the chain w a degreaser and relubing - that noise could be road grit - happens to be when i ride in rain and a good cleaning and relube is my remedy

If water got in, which is very possible, than odds are that you're hearing the effects of rust. It's possible that if you fieldstrip the BB now, the damage might be minor enough that it can be saved by cleaning and greasing (not an option with cartridge BBs).

However, it should still last for quite a while without service, and odds are the damage is already done, so you might as well finish your trip and replace the BB when you get home, or keep riding it locally until it finally dies.

For future reference, BBs vary greatly in their rain resistance. On BBs which can be serviced, the grease itself can also make a tremendous difference. If you, like me, expect to ride in all weather conditions, factor that in your choice for the replacement BB.

Thanks! I finally though of taking my chain off and spinning the pedals to listen for noise. I don't know why I didn't think of this before!
The noise is the chain...it got pretty dirty riding on gravel trails and I didn't de-grease it. I just wiped it as best I could and re-lubed it. Does it destroy your chain when it's really dirty?

Yes and no. Destroy is too strong a word, but dirt can shorten a chain's life. I said can instead of will because only dirt inside the chain counts. What's stuck on the outside doesn't have any effect until/unless it works it's way in.

OTOH, a chain that's dirty and gritty on the outside of the rollers and between the plates increases chainring wear. That's probably what you're hearing. There's no easy answer and every rider finds his own balance between how much dirt he can live with and the time and effort to keep a clean chain.

good deal - enjoy the rest of your trip

Thanks!