I am trying to help a friend with his old bike. Upon stripping out the old crank to over haul the bottom bracket, I find this pitted (?) alum alloy chain rings. Al three of them and its like cancer. It must have spread form one to the other. Crank arms are in perfect condition. Its also alum. alloy. Look at one of the pic, its like the alum starts to de-laminate, but I am not sure if its forged?
