Originally Posted by
cyccommute
As I stated above, the main reason for using Teflon coated cables is to avoid corrosion of the cable when exposed to salt. Stainless isn't resistant to salt corrosion. I've pulled many cables out of housing that is lined but the cabling was coated in salt induced corrosion products.
I disagree. First, cables need adjustment after initial installation. That is a given. New inner cables always require some adjustment of cable tension. Others have suggested that the cable tension adjustment is due to the outer cable settling into the ferrules but cable tension adjustments are always needed even if you are using old housing. The simplest explanation for new cables needing tension readjustment is elongation of the wire cable as the cable strands twist slightly tighter when put under tension.
Cables of all varieties do stretch, from bridge cables to crane cables to bicycle cables. There is even a formula for calculation how much a cable will stretch under loads based on the load and the diameter of the cable.
Well, we have to separate elongation under load (elastic deformation) from a permanent slight elongation when a new cable is first put into service as the strands bed-in against each other and/or settle into the end ferrules. The first type occurs with every shift and is automatically compensated for while the second type occurs initially and is why minor adjustments to the cable "tension" are needed for the first ride or two after a new cable is installed.
I try to compensate for the bed-in type of elongation by pulling firmly on the cables before making my initial shifting adjustments. I usually works so only very minor adjustments are needed after the first ride.
BTW, if you do use teflon coated cables, be certain to scrape the coating completely off where the cable clamps to the derailleur. Otherwise the cable WILL slip no matter how much you tighten the clamp bolt.