Originally Posted by
Popeyecahn
Thank you, this is what I was thinking while considering using an idle Ultegra RD-6500 GS with the 7sp 13-34 freewheel I just received. The 6500 will only handle a 28t from what I read and wondered what would be the limiting factor. You have ably pointed this out. On to finding an MTB rear der... Oh snap the Fisher has a clean one from 1988!
You are correct, both the RD-6500-SS and RD-6500-GS have the same maximum cog rating, though Shimano's official stance, according to my catalog, is 27T.