I rode coast to coast in 1977, think about the equipment we used! My two biggest problems were tire related and spokes. Learn how to boot a tire, patch tubes and carry some spokes and know how to install them. IIRC I did replace the chain near the end of the trip. If you start with a well maintained modern bike you shouldn't have too much go wrong.

If you understand the basics of how a bike works you can usually limp along to the next town and find a bike mechanic there.

Aaron