Originally Posted by
noodle soup
The PTFE coating on Shimano cables tends to peel and flake off, which can gum up inside the housings(actually causing increased friction).
Pretty much this.
I have Shimano with the optislick crap and at what I estimate to be 1200 miles, I and the LBS agree I'm probably in need of cable replacements, at least for the RD. They said the regular, non opti should go for 3000ish miles.