Originally Posted by migrantwing

With regards to my idea of running PTFE liner from the downtube cable stops to both the front and rear derailleur, I found some stuff (pic below) that may do the trick. Available in different OD and ID, and cheap as chips, too.

Just need to measure the ID of the cable stops and barrel adjuster screws to make sure I get the correct size of liner. It's gonna be a tad tricky as I don't want the liner to be too large for the hole, or too small that it will fall out easily and end up gathering at the bottom bracket like a wet sock