Stainless inner cables versus galvanised?

[Bolt]

Susceptibility to corrosion aside, are there any other factors to take into account?

[zigzag]

good quality inner cables are slick/smooth and i've never seen one made out of galvanised steel

[Oxford_Guy]

There do exist polymer-coated ones e.g. http://www.chainreactioncycles.com/shimano-dura-ace-9000-road-brake-cable-set/rp-prod130988

But AFAIK they're stainless steel, but coated, not galvanised

[zigzag]

coated shimano inner cables should never come in contact with a bike, let alone be installed!  

[Canardly]

The stainless ones can and do snap. Why anyone would want or trust a galvanised cable I cannot imagine.

[Kim]

Galvanised are cheaper, and some people concentrate on the price with no regard for the cost.

And sometimes people buy galvanised because they aren't paying attention... 

[Torslanda]

I only ever use stainless, have done since day one.

I get to replace galvanised all the time.

[Brucey]

there are such things as coated galvanised brake cables; I have no idea who makes them but I have seen them coming out of bikes that are being serviced.

If you have to save money on buying cables, buying galvanised brake cables is a way of doing it. They can last reasonably well if they are lubricated correctly, but are always a little more draggy than well-polished stainless inners. By contrast if you try and stick galvanised gear wires into a lot of indexed systems they simply won't work at all well.

The corrosion issue is a bit of a red herring; by the time conditions are such that a galvanised wire is in danger of corroding, either a galvanised or a stainless wire will have become rather draggy.

Stainless wires with no coating are made to be low drag by being polished. Standards of polishing vary a fair bit and if it is overdone, the strands in the bundle are thinned too much and may be in danger of breaking more easily.

Coating of stainless wires can also help reduce friction but (esp if the housings are badly prepped or there are abrupt kinks in the housing near a ferrule) the coating can come off the cable and maybe start to clog it. Shimano have produced several different coating types, so have others, and they vary but none are 100% immune from this.  IMHO if you have a particularly finicky system (such as shimano 10s road with underbartape routing) then it isn't a bad idea to use the best polished stainless inners with no coating (eg the latest Jagwire ones) and a suitable lube. If the system works OK with those inners it will probably carry on working for longer than if a coated cable is used.

cheers

[Kim]

The corrosion issue is a bit of a red herring; by the time conditions are such that a galvanised wire is in danger of corroding, either a galvanised or a stainless wire will have become rather draggy.

I'd say this depends entirely on the cable routing.  If you've got loops of continuous outer where water can collect, a galvanised cable can become unusable in a wet weekend, where a stainless one would be merely 'a bit crap'.  Obviously trying to prevent water getting in in the first place is the best thing you can do to improve matters (I've had some success with greasing the cable where it exits the outer, and strategic application of tape to cover the slots in the front of MTB levers).

Coating of stainless wires can also help reduce friction but (esp if the housings are badly prepped or there are abrupt kinks in the housing near a ferrule) the coating can come off the cable and maybe start to clog it. Shimano have produced several different coating types, so have others, and they vary but none are 100% immune from this.  IMHO if you have a particularly finicky system (such as shimano 10s road with underbartape routing) then it isn't a bad idea to use the best polished stainless inners with no coating (eg the latest Jagwire ones) and a suitable lube. If the system works OK with those inners it will probably carry on working for longer than if a coated cable is used.

Interesting.  I've tried coated cables in the past and been underwhelmed by the performance compared to good quality stainless, this is probably why.

[robgul]

Galvanised cables are in the same league as "rustless" spokes - AVOID.

The difference in cost between the cables is pretty marginal in the scheme of things when you get to replace them.

Rob

[Oxford_Guy]

When I was running  Campagnolo shifters on my touring bike, I did find the genuine Campag inner and outer brake/gear cable/housing to work better and last longer than third party stuff, but I'd be interested to hear the experience of others, as will be putting these shifters on another bike once they come back from being refurbished.

[Brucey]

Galvanised cables are in the same league as "rustless" spokes - AVOID.

as with many things they are not all the same. For example modern 'rustless spokes' are electroplated with the least amount of plating possible and will last oooh, about a year or two before they rust.  By contrast rustless spokes as they were made at one time were hot dipped (I think); at least they had much thicker coating on them and would last maybe a decade before there was any real danger of rust.

BTW stainless steel inners are not immune from corrosion; if an outer fills up with water and stays filled up with water (eg on a bike with a long cable housing run for an IGH or a brake, with a  slopey cable run down the chainstay) then the conditions inside the cable can rapidly become anaerobic, which means that the protective oxide film on the stainless steel cannot re-form.

 I have seen many stainless inners emerge from such housing runs and they are usually black-coloured at the low spot. The blackness is a sign of corrosion; often the  black coloured part of the cable will break if flexed a few times and if it is really bad then the cable inner will break inside the housing and if it comes out at all, it will  come out in two pieces.

I don't think that this happens very quickly, nor is it very likely on many bikes because of the way the cable runs are arranged,  but even so the main protection from this (which applies whether the cable is stainless or galvanised)  is stopping the water from getting in and/or lubricating the cable properly. BTW there are ferrules with external boots and seals that prevent upwards-facing housing ends from filling up with crud; you need to use these if you want your cabling to last in the weather.

BTW a straw poll of cables that are being replaced with new in an LBS near me produced an interesting result; the #1 cause of a cable going bad appears to be that it was never installed correctly; installed without decent lube, without the correct ferrules, with badly prepped housing ends, with poor cable runs that allow water in too easily.  In many cases if the original cable was reinstalled with these faults corrected, it would carry on working.

A final point is that wherever a cable flexes, the strands in the cable will rub against one another.  This rubbing can hasten a cable failure; when industrial wire ropes are installed they are impregnated with heavy grease to help  prevent such rubbing damage. Thus installing cables bone-dry inside shifters is asking for trouble, and coated cables cannot easily be lubricated (within the strand bundle) whilst the coating is intact.

cheers

[Kim]

So what's the preferred lube for cables?  I've tried GT85, and I've tried chain oil, and (with good quality stainless cables and PTFE outers) I've found that dry cables give better results.

[Samuel D]

I use Shimano Cable Grease, part number Y04180000. It noticeably reduces friction, lasts a long time between applications, and seems to protect the cables well through wet winters. Better stuff may exist but this does the job adequately.

[rogerzilla]

Shimano do both.  The stainless ones stay smoother for longer.  If you see SIS cable inners on the Bay of Thieves of unspecified material, they are almost certainly galvanised.

[Brucey]

re cable lube; a major problem is that the type of cable housing liner material is not always known and many types of liner tend to swell up or soften when lubricants are used.  Oil alone may (in addition to reacting with the liner) just run out of the cable over time. Many greases don't have the right viscosity properties (e.g. they are too thick when stationary or in low speed shear) and contain oils that may react with the liner. If you use grease it may separate over time, so that the oil migrates out of the housing, leaving the thickener only, which may be a chalky substance that is not a lubricant in its own right.

The possible reaction of oil with the liner material is complicated; most mineral oils contain a mixture of molecule types, and it is virtually certain that some of them will react with any given polymer. With synthetic oil, it is a monomer so it will either not react at all or it will all react. One hopes that the latter is quite unlikely.

You can buy the shimano cable grease which presumably works with shimano cable housings. I don't know what is in it; it might be silicon grease?

Some folk reckon silicon grease is the right stuff for cables; it is less likely to cause swelling/softening of liners, I think.

Cables with good ptfe liners will work OK if they are installed dry (which is how many campag cable sets are I think), but then again might last even longer if a good lube is used.

You can buy 'rock'n'roll' cable lube grease, that is one of the few lubes that is specifically meant for cables. However a chum tried it and it must have separated or reacted with the liner or something; he was left with a chalky, bindy mess after only a few months.

I have carried out some experiments with a cheap product which is '151 super spray grease'. This is a synthetic grease and it is suggested as being suitable for plastics. It doesn't seem to dry out or separate at any speed and doesn't seem to dry out to leave a chalky residue. I think it is slightly too thick for gear cable runs but it works really well inside many pumps.

I normally use shimano cable housings (sometimes jagwire), and I lubricate the (polished stainless) inners with a little finish line ptfe grease (which uses a synthetic oil base), and then I add a little synthetic gear oil to the cable inner as it is inserted.

 The idea is that the synthetic oil isn't going to react with the liner (fingers crossed). The grease/oil mix (about 30-70) is thick enough that the oil won't simply run out of the cable, but thin enough with low sticking friction that the cable will run smoothly. If the oil does eventually separate out of the grease, most of what is left behind is (I believe) PTFE, not some chalky rubbish, i.e. it is still a lubricant.

 If the upper end of the cable is vulnerable to water ingress (as is commonly the case with flat bar controls) then using a little Vaseline at the cable entry seems to help deter water getting into the cable run. Vaseline is too thick to be used in the full length of most cable runs.

 Normally good quality cables that are set up this way work OK for several years, (or the fatigue life of a gear cable inner in intensive use with STIs) but.... nothing lasts forever and systems do vary in their sensitivity to the quality of cable movement. 

There may be a much better approach than this which I have not tried.

cheers

[mzjo]

Galvanised cables are in the same league as "rustless" spokes - AVOID.

The difference in cost between the cables is pretty marginal in the scheme of things when you get to replace them.

Rob

In the last 50 years I have used lots of "rustless" spokes and not had the slightest problem that I would attribute to quality (but as noted above, the older ones were a different quality and most of mine are in that category).
OTOH I have known some crap cables (particularly rough spirals on some that just snag in the outer and refuse to work efficiently). I have never had any doubts about chucking crap cables.

[rogerzilla]

ISTR that "rustless" spokes are actually stronger than stainless ones when new but (a) UTS isn't that important and (b) they won't stay like that for long

[Brucey]

the coating on the outside of a spoke has precious little to do with the strength of the metal within; spokes vary in strength (quite a lot) regardless of whether they are stainless or not. 

The UTS is associated with fatigue life provided the spokes have similar levels of integrity. But in practice they don't, for all kinds of reasons.  Thus cheap spokes are cheaply made in cheap steel and may have all kinds of flaws that may limit fatigue life.

 The interesting thing is that the kinds of galvanised spokes that were used on countless raleighs and so forth BITD were usually of pretty good quality; I had one or two batches that were badly made but then I have in stainless steel spokes too.

cheers

[rogerzilla]

Well, stainless steel isn't coated - it's always a risk replacing carbon steel "Jesus bolts" with stainless, as stainless isn't always as strong.

[Bolt]

Thanks for the interesting responses to my OP which was prompted by some idle pondering while attempting to replace a galvanised brake cable before realising that I hadn't a spare of any description.  So I was forced to refit the original but cleaned up the poorly cut ends of the outer, fitted new ferrules and lubed with silcone oil and all was well, I'll see how long it stays like that!