Originally Posted by
bikemig
I like the shimano 600 group by and large but I am not a big fan of the 600EX long cage rear derailleur (RD 6207 GS). It works but not as well, IMO, as the later shimano MTB RDs. My Cannondale 1985 ST 400 came stock with a complete shimano 600 group. I found the shifting to be less precise than I liked. I kept the 600EX headset and brake calipers but swapped out pretty much everything else.
Nice Cannondale(!), they had some really good colors back then (mine was the light metallic green).
The pre-SIS Shimano derailers would have really benefitted from having some kind of body angle adjustment, but there is no external means of adjusting either the B-pivot or cage-pivot springs on these derailers.
But just as when I couldn't get my Cyclone GT derailer to swing forward enough for responsive shifting on a 13-28t 6s freewheel (where I had already removed the B screw and had to remove further metal from it's stop lug), the Shimano derailers can have their spring tensions revised internally by drilling new spring-holes, or by grinding some metal off of the bent tab on the stop plate.
These are much like Simplex derailers, which do often have the cage pivot locknuts or alternate spring holes which allow for adjusting the dersiler angle to the freewheel size.
Shifting is radically improved with best adjustment, versus random combinations with factory pre-settings. It's one of those things (just like chainline) that can make or break a bike's ride character imo, so I will take the time to do it one way or the other.