Cable Housing - when to replace?
 

My Simplex to Shimano SIS conversion is plugging along.

The question now I have is regarding cable housing. The existing housing seems OK. If I wanted to match the original color, I'd probably have to order it and end up with way more than I need (which is maybe 1 1/2 ft.)

There's also apparently "SIS" compatible housing along with teflon lined, unlined, etc.

So my questions are:

Do I need to replace it?
Do I need SIS compatibility or is that just a label designed to get me to spend more?

I'm thrifty (cheap) if you haven't noticed ;-)

Some older housing tends to compress longitudinally as the cable is tightened, and this will throw off your indexing. Modern brake and shift cable housing tends to be nearly incompressible, which makes for a firmer feel on the brake handles and more accurate shifting. If your old housing is in good condition, why not try it out and keep it if your results are satisfactory?

As usual, Sheldon has the definitive word on the matter:
http://sheldonbrown.com/cables.html

Thanks. Looks like new housing would be prudent.

That was my thought. You should buy it from Sheldon, as well. His prices are good and he ships within minutes.