And I'd add that bikes are more tolerant of that scuzz than you might think.

When I was in Houston last month, I rebuilt my mom's bike, a '71 Schwinn Breeze. She'd bought it used in 1974 when she immigrated to the USA. All through my childhood I remember it being a grimy bike, with the back gearhub always caked in black stuff. Getting all the parts clean took exhausting amounts of scrubbing - all that black stuff I'd remembered was a thick coat of sand cemented with dried oil and grease. Asking my parents about its history, it seemed to be used pretty politely in the past 34 years...it seems that all that junk was from the original owner using it between 1971 and 1974, likely on Los Angeles beaches.

After the rebuild, tons of Simple Green and new grease and new balls, the bike rides like a dream. All the bearings are silky smooth. Remember also that these are cup-and-cone bearings with no rubber seals or anything like them.

So don't worry so much. Take it easy, and when you are feeling ambitious (or maybe right now as it's on your mind), give the critical parts a detailed, surgical cleaning one by one.