skiingfury

I purchased the Jagwire Road Pro kit for a flatbar road bike that I am building. The kit shipped from Amazon, not a 3rd party, so I don't suspect counterfeit.

When I cut the brake cable, I was surprised to see that it was linear stranded, like SIS housing. At first I thought that they had made a mistake in manufacture, but their website indicates that the KEB-SL brake housing is in fact linear stranded: Jagwire Housing Guide | Jagwire.

When testing brake function, I noticed that the brake housing was deforming in a tortured fashion that was causing the plastic to change color. After test, I inspected my brake housing and found that some of the strands had protruded from the housing, though the ferrule. It turns out that linear stranded brake housing is still a bad idea- I don't know what they could do to prevent this sort of failure in such a design. I am surprised that they are selling this product. Has anyone else experienced a similar result?

FBinNY 

Low (SIS) helix housing like yours requires a ferrule with a structural flat bottom to support the strands. The right ferrule is critical because the conical (drill point) bottom of typical ferrules causes the wires to work toward the hole and ultimately extrude through.

IMO - despite being trendy low helix isn't well suited for the high compression that brake cables call for. The coil spring high helix housing does a better carrying the load, and is immune to that tendency to extrude through the center. My other objection to low helix housing for brakes is the failure mode. Traditional housing is steel on steel, and when it fails under load may partially collapse. However the long strands of SIS housing depend on a wrap to keep from bursting to the outside and buckling causing total loss of the brakes. Yes, it's rare, but I can't fathom replacing something that work with something that is less well suited to the task.

BTW - despite not liking that type housing for brakes, I believe that the folks at Jagwire know their shist, and wonder if you simply used the wrong ferrules from the kit. The other possible cause may be that you have a defective ferrule. Plastic ferrules for this housing have small steel thrust washers pressed into the bottom.

skiingfury

That makes sense about the ferrule, but they should supply more of their "special" ferrules in that kit. It still doesn't address the fact that I was seeing the beginnings of a burst failure mode when testing my brakes.

I also agree that high helical wasn't broken to begin with.

FBinNY 

There should have been at least 4 (index) ferrules, either plated brass, or plastic with steel washers. However, they may not make clear which are which ain the instructions, nor the importance of using the right ones.

skiingfury

For brake, there were 2 'standard' ferrules, and 2 of the 'Pop' ferrules were where very long. I had some shortish bends to make with the canti brakes, so I couldn't use the long ferrules and used some that I had in my drawer.

xenologer

This is why, for Compressionless housing, I like Yokozuna's 'Reaction' system over Jagwire.
Yokozuna has the linear strands like you've seen, but they are then surrounded by the coil spring style so they can't burst fail under braking loads or unravel at the ends.

The design just makes more sense to me.

just like the Jagwire though, correct ferrules remain important - for a different reason though; Reaction housing is fatter than normal and other ferrules won't fit.