Originally Posted by
Panthers007
Well, the 4mm housing would be reserved for derailleur-cables, whereas the 5mm would denote it's use for brake-cables - which has to be stronger/heavier than derailleur-cables. They even come in larger sizes.
You can use a brake-cable to shift your gears. But don't use gear-cable for your brakes. No. No. No.
I figured that WNG (the 2nd post) was asking about the difference between 4mm and 5mm
shifter cable housing - he asked about
SIS cable which is shifter stuff, and since he said 4mm and 5mm I figure he meant housing.
before indexed-shifting, the needs of brake and shifter-cable housing had only to do with differences in force (through cable tension), as Panthers007 says. But since the advent of indexed shifting and its need to keep precise cable-pull increments, brake cable housing and shifter cable housing are very different animals. brake cable housing has less precision under compression than modern shifter cable housing.
brake cable housing can be used for shifters, but ideally only with non-indexed shifting (as I do on my
Schwinn Traveler).
brake cable housing is nearly always 5mm outside width.
shifter cable housing comes in 5mm or 4mm outside width, as my earlier post assumed and well biked noted. So far as I know, there is no functional difference between 4mm and 5mm cable housing.
and well biked: your pinarello build is absolutely gorgeous. kudos.