I am very much a novice when it comes to derailleurs. As a matter of fact that is why I just bought a used road off craigslist--so that I can learn how to maintain/adjust derailleurs.
I am dealing with my rear derailleur at the moment. I understand cable tension is very important for smooth shifting, and said cable can be finely adjusted by turning the barrel adjuster on the rear derailleur, itself. Cool. However, I noticed I also have two barrel adjuster on the frame, on the upper portion of the down tube--one for the front derailleur and one for the rear derailleur. Why do I have two barrel adjusters for the rear derailleur (one on the frame and one on the derailleur) and which one do I use to make adjustments? Or do I use them in tandem somehow?
Thanks in advance.