While I was in Florida my chain started skipping around in the two large rear rings. I put the bike up on the stand yesterday and discovered that the rear derailleur was way out of whack. It never got to the last low gear ring and slipped off and on the one next to that. I followed some youtube instructions first tweaking the high gear (outboard) delimiter screw to get things right out there. Then I switched to the low gear (inboard) delimiter screw and was unable to get a good position even with the screw backed way out. Then I remembered there is a cable barrel adjuster so I tightened the screw back to what I guessed was a reasonable position and was then able to get a decent adjustment with the barrel.
So, how do you figure out when to mess with the barrel and when to mess with the screws? Is there any "optimal" position for the screws or barrel to start in? Half way in/out on all three?