Ok so I'm looking at the 3 front rings and the cassette on my bike. They are starting to round off so I assume it's about time to think about changing them out. Can I upgrade from Tiagra to, say 105? I'm sure I can go to the LBS and get parts, but I've been wrenching on my motorcycles for the past 30 years and prefer to learn/do it myself.
Further questions would be where is a good place to locate parts?
In the mean time I'm also looking at the local shops for a basic mechanic class that will help answer these questions. In the mean time I thought I'd start here.