SIS-gear cable outer, that has longitudal "fibres" instead of "coiled spring" should never been used as brake cable or you will risk loss of life and limb.
Have a look at Odyssey Slic cable, and Goodridge compressionless brake cable.
Both of these are of the longitudinal fibre type, rather than the coiled spring variety.
The issue with using something like SIS cable is that (I am conjecturing here) it's narrower, so the chance of snapping it is greater.
Brake cable housing is, normally, pretty shit, it benefits from being changed to the same type as gear housing, albeit you need it to be of a larger gauge to accomodate the thicker cable.
Have a look at Odyssey Slic cable, and Goodridge compressionless brake cable.
Both of these are of the longitudinal fibre type, rather than the coiled spring variety.
The issue with using something like SIS cable is that (I am conjecturing here) it's narrower, so the chance of snapping it is greater.
Brake cable housing is, normally, pretty shit, it benefits from being changed to the same type as gear housing, albeit you need it to be of a larger gauge to accomodate the thicker cable.
IMHO etc and blah.