Originally Posted by
FBinNY
NO. this is wrong.
The limit screws are exactly what their name implies. They set the extreme inside and outside limits to the derailleur range. Think of them as the concrete barriers along the sides of a bridge so you can't drive too far to the side and into the drink. Te barriers determine the road width, but you have to choose and drive in the lanes.
The derailleur's mechanism hangs from the cable, and that determines it's position.
However, in practice there's an exception. Most derailleurs (both front and rear) are designed so the cable is overly slack in the slackest position (high in rear, low in front) and the derailleur is allowed to rest on the corresponding limit. So, the inside FD limit does affect the trim in low, but that's the only gear where it's used for trim.
This is assuming that the derailleur limits are adjusted with the cable being slack or not attached and that it's allowed to rest on the stops (the correct way to setup a derailleur)
If the cable is attached to the derailleur and then the limit screws are adjusted, the derailleur won't be resting on the stops.
case in point, OP adjusted low limit and now cable tension has clearly changed. thus, it wasn't resting on the limit stop.
OP should have an inline barrel adjuster on the cable somewhere (at the shifter) that should help him trim the noise out.
the better question should be: why did the OP feel the limit needed to be adjusted to allow more movement inward.