Yellow Saddle
Guru
- Location
- Loch side.
Let me see if I can get you onto the other two as well and we have a 3/3 agreement.Well, at least we agree on cheap.
Coarse as opposed to fine? The cables I fit are invariably far smoother and finer than those they're replacing - though admittedly I probably leave that longer than I should.
Gritty? I haven't come across any grit - poor storage perhaps
Gear and brake cables are made up, as you know, from steel wire wound helically in alternative directions, until you end up with a wire rope. The amplitude of the helix is matched to the minimum radius the cable is meant to be bent around. If the bend is too small, some of the strands will take a longer path than others and the cable will constantly have internal shifting of the wires against each other. But if you stay within the helix' limitations, a bend does not cause some of the strands to become shorter or longer than its counterparts.
Clarks and most cables scores well on that requirement.
Then, the individual strands, as you know, are round steel wires. The material itself could be smooth or course. However, we reserve that property for the way the cables are treated after the winding. If the wire itself is course, I like to say it is gritty. In other words, the wire has plenty of aberrations on it, typical of galvanized cable or cable pulled through a faulty die. To get rid of that grittiness, the wire should receive one extra manufacturing process - pulled through a smooth die and, made of a material that pulls into better and smoother shapes, like stainless steel.
Once the cable has been wound into its required thickness and the right length of helix, it can be left alone as is, or machined further. Left alone as is creates a daisy shape should you do a cable section and look at it head-on. The daisy shape is not difficult to imagine and you can actually see it if you look at a cable. Now imagine that shape being pulled through a soft plastic liner, around corners and under force. This is typical in a brake cable on a bend. The daisy shape will not glide well over the plastic liner and abrade it on the inside radius of any bends in the cable. To improve on that shape, another process is applied - a smooth die that flattens the cable's outer so that the daisy shape becomes more tube-like. Now it is smooth, not course and not gritty.
People are fickle and love to believe adverts and brochures. Don't think you're immune to this. Also, once you've learnt something at school it becomes gospel and people never again question stuff they've learnt at school. If your school taught organic chemistry you would have been exposed to Teflon, a slippery substance that improves everything it is used on. Aeroplane cable, frying pans, ground up in motor oil (I kid you not) and also on bicycle cables. Jagwire plays that tune and coats its cable with Teflon. However, Teflon is not abrasion resistant and soon rubs off and clogs the cable lining. This is visible if you remove the back inner cable from the housing after a short while of use. The clogging and jamming effect can also be felt it you manipulate the cable after a few hours of normal operation. It is smooth at first and then sluggish.
The best cable until two years ago wasn't coated. It was made from stainless steel wire, not lubricated but smoothed out in a die.
Nowadays the best (smoothest operating) cable is coated with a coarse (yes it is contradictory) polymer coating that reduces friction dramatically but also resist abrasion. It is made by Shimano.
How does one test a cable for smoothness? You compare it. Wrap a length of inner and outer around a pole/tube of diameter 60mm or so. Give it 6 turns and tape it in place so that it doesn't uncurl. Now move the inner in and out in a simulated gear change or brake application. The results are startling. Clarkes is the worst, then BBB, then Jagwire then old Shimano, then Shimano M-System, then standard Shimano then new Shimano Polymer. Try it and tell me if you disagree.
My photo doesn't do justice to the three types, but it does show the difference between a smoothed and non-smoothed cable.
Here is an expensive Gore cable in action, or is that inaction. The Teflon liner separates from the cable and jams the channel. You can actually see how gritty the cable is underneath the Teflon liner.
here is the latest Shimano polymer coated cable. Smooth as butter and resistant to abrasion. It does however peel off at the cable anchor.
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