11-04-09, 08:44 PM
I took apart a 1980's shimano rd-2505 rear derailleur, 6spd freewheel 3 up front, on my shogun 500. There is a plastic disk with notches on the face. It fits over one of the jockey wheels. Unfortunately, a week later, I forget which wheel and exactly how. Anyone familar with this? What exactly is it for?