Linear vs Spiral Wound Shift vs Brake Cable
 

I had come to the understanding that shift cable should be linear and brake cable should be spiral wound, so why do Jagwire cables, both shift and brake, use the same linear composition and should I change my brake cable to spiral wound?

From Jagwire website:

http://bikeforums.net/attachment.php...hmentid=521558

The linear composition is to make the cable housing compressionless. That's necessary for index shifting.

You are correct in noticing that at least some of the Jagwire brake cable housing also uses the same linear composition. If that wasn't reinforced by the kevlar sheath the greater cable tension used during brakeing would cause the cable housing to blow out at the curves.

Personally, I much prefer the compressionless Jagwire brake cable housing for use on mechanical disc brakes.

It's a bit of a minefield on the Jagwire website regards inner and outer cables. I run the Road Pro set at the moment, but am going to change out the Teflon coated inners (both shift and brake) which are black. The black Teflon coating rubs/wears off at points where they attach at the derailleurs and brakes by bolts, so thought that it may be wearing off inside the housing and liners also. I am going to switch them out for some standard slick stainless inner cables with no Teflon coating.

I will spend the next few hours looking at all the different inner and outer cable offerings and try and come to some conclusion :)

I agree, I never saw the point to having coating on both inners and outers, since the coefficient of friction of PTFE vs steel is almost the same as PTFE vs PTFE. In addition the coated inners are difficult to clamp securely unless the coating is removed. I just stick with lined outers and die-drawn (slicked) stainless inners. Sometimes more is not better.

Indeed! It's all a load of bumf. I had a few problems with dialling in my derailleurs when on the move, I later realised that the clamping wasn't sufficient as per your comment. I scratched off all the black Teflon coating at the anchor points and reattached the cables to the derailleurs. No problems occured.

I'm also toying with the idea of running some cheap Teflon lliner down the downtube for both derailleur cables and using some sort of rubber boot at the clamp bolts to stop water and debris ingress. A cheap DIY sealed cable kit.

Die drawn cable, has its outer wires flattened, to be smoother ..

FWIW I have a recent Brompton I got Used, they use both coated cables and lined housing..

I changed brake levers & when I replaced both with Longer, found the cable coating rubs off ,

where the cable sees the most friction, in bends..

I solder the end before cutting the cable on My Bike. Zn treated steel , thats easier to do , I grease the cable to resist rust .

( Stainless takes a silver based solder & a different flux)



Jagwire has a Kevlar braided sheath housing of linear low compression type, new, for Disc mechanical brake use,
though spiral square wire housing is adequate and time tested.

Compressive brake cables won't rob brake force directly but will increase lever travel by some amount(how much?). That could be good(for feel) or bad(if you run out of travel before generating enough force). I understood that the argument against the newer linear brake cables is that they are very stiff and thus difficult to route (could it even impact steering?), but I haven't tried them. It makes sense though.

In my experience the black coated cables work great. They're very smooth and they maintain very low friction for a long time. The coating is hard and works better and doesn't slough off like polymer and teflon coated cables, which can gum up the action.

The Jagwire compressionless brake housings I've used have a Kevlar wrap whereas the Yolozuna housings have flat steel wrap and are a fair bit larger in diameter than the Jagwire housings. The Jagwired housings come with a spiral wrap section for increased flexibility going round the bend from the ramps to the tops of the bars under the tape, but I don't use it.

Interesting, to me anyway, thread. Thanks all.

Glad I posted in that case :)

With regards to my idea of running PTFE liner from the downtube cable stops to both the front and rear derailleur, I found some stuff (pic below) that may do the trick. Available in different OD and ID, and cheap as chips, too.

Just need to measure the ID of the cable stops and barrel adjuster screws to make sure I get the correct size of liner. It's gonna be a tad tricky as I don't want the liner to be too large for the hole, or too small that it will fall out easily and end up gathering at the bottom bracket like a wet sock :)

http://bikeforums.net/attachment.php...hmentid=521718

I'm curious... What's the source of the "stuff"?

Anything can be used. You can buy Jagwire liner, Nokon liner, Alligator liner etc, but any liner will do. You could also use heat shrink tubing if you wanted or something like the liner that is used in 3D printers. Anything that is light and flexible and slightly larger diameter than your inner cables, obviously.

Here in England the majority of stuff is a lot more expensive than in the States and we don't have the plethora of choice like you guys do. It makes people like me do DIY jobs on things like this :) Alligator i-link gear or brake cable set is around $80-90 USD here, for each set! I'm not gonna pay that.

Interesting, and makes sense. I'll keep that in mind when the time comes for me to replace my front brake cable. (I run mullet brakes, BB7 up front, rim behind.)

Probably won't make too much difference on the front. Riding recumbents, we have some long cable housing runs. The longer the run the more compressionless housing helps. The downside is that the Jagwire compressionless brake housing is about twice as expensive as typical housing.

Surly Disc Trucker also requires a long rear brake cable run. Jagwire compressionless housing worked well for 1-1/2 yrs but frayed at rear ferrule after which it compressed a lot, heh. In the old days I rode racing bikes with Campy brakes & there wasn't that much compression on full-length rear housing runs. Spiral-wound housing never failed dramatically for me.

Linear cable housing is virtually compressionless. However, it has relatively low sidewall strength under high load. If you put a high load on the inner cable, it can "slip" between the linear strands and cut/rip through the housing wall.

Spiral-wound cable housing is relatively "mushy" under linear compression, however it protects the housing very well: it can sustain extremely high loads without allowing the cable to cut through the housing.

Obviously, it makes perfect sense to want to use to use compressionless housings for both applications - shifting and braking. Unfortunately, it is not that easy.

Shifter cables work under low loads. For this reason it made perfect sense to use compressionless cable housings for shifter cables from the very beginning.

Brake cables work under very high cable loads. Because of that, initially it was impossible to use linear (compressionless) cable housings with brake cables: the danger of having the cable to rip through the housing under emergency braking situations was too high. For safety reasons, brake cable housings were spiral-wound, which reduced the crispness of the brakes but hugely improved their sidewall strength.

However, with modern materials and technologies, it became possible to make cable housings with linear metal strands (compressionless), which at the same time have sufficient wall strength to withstand any real-life brake cable load. Kevlar is one of the materials that is used to reinforce brake cable housings specifically for that purpose.

And that is exactly what you observe in case of Jagwire brake cables: the housings use Kevlar sleeves, which gives them sufficient strength for braking applications. Because of that, the housing can finally abandon the traditional "mushy" spiral wind and take advantage of compressionless properties of linear metal strands.

So why aren't you using Campy brakes on your Disc Trucker? Not exactly a apples to apples comparison is it.

Very interesting and informative. Thank you for your description and evaluation.