I am switching from a 7 speed_(13 to 24) freewheel to a new 9 speed_(12 to 23) cassette. A new wheel as well. I have an Ultegra long cage RD that was next to free so I will use it even though it's a standard double up front.
Does the new 9 speed chain need to be any longer than the previous 7 speed chain or can I just use the old one as a guide for the length.
Also I am going from 42_53 double to 39_53 chainrings. I doubt if that factors into anything.