sticky shimano gears

kevin69

i have shimano dura-ace 7800 gears and occasionally the front and rear derailleurs
will stick slightly, with a fewer seconds delay between moving the levers and
the shift happening. Very occasionally the front derailleur will fail to shift down at all:
in this case i have to shift up and then down again.

I can't replicate the problem on a stand, and the derailleurs themselves seem to move
smoothly, so i'm thinking that the problem might be the cables, which are about 3 years old.

Does this sound right?
If so, what gear cables would you recommend?
Are the ptfe lined cables worth the extra?

thanks

nicklouse

sounds like mucky/rusty cables. any as long as they are at-least stainless.