Originally Posted by
timdow
9-speed road and mountain are the same. This is not the problem.
When you are in the largest cog in the cassette (smallest gear), you should be in the small ring in front. If this is the case, it's probably not the chain being too small. This would be a problem in big-big combination, but that is a gear combo that you shouldn't be using, anyway.
This is what I suspect the issue is:
When in biggest cog on the cassette and the small ring in the front, is the chain squished between the derailleur pulley and the cassette with no gap? This is why folks are asking you about the "B" screw, which will adjust this.
Does cranking the "B" screw fix the issue?
Right, I avoid going more than one past the middle without switching chainrings - so not likely to hit chain size limitation. Though I think I accidentally got to that position while tuning the indexing, and the chain didn’t break.
The issue shows up when I use the large chainring and becomes more pronounced as I shift towards the smallest sprocket (highest gear?) on the cassette. So the derailleur is way too far from the cassette to pinch the chain. That’s why I suspect it’s either indexing slightly off or the actual feel of a different cassette.
B screw is a bit of a mystery to me. It doesn’t seem to be doing anything! The YouTube videos show the derailleur visibly and obviously moving towards and away from the cassette sprocket as the B screw is adjusted. I have completely removed the B screw (by mistake), then screwed out all the way in to the stop, and I have to talk myself into believing that I can barely see the derailleur roller moving up and down. Still trying to figure out what’s going on there… But the chain isn’t pinched by the roller to the best of my understanding, and it would happen in low gear anyway, not in high gear where I actually get the growl.