"Streched' Gear Cables

[LOOK695]

Cables don't become longer. They may stretch elastically and if yoiu're on a long cable, like a tandem's rear brake, you can actually feel it. However, like an elastic band, they return to their original length as soon as you let go of the brake/gear lever.

 

However, it is not the inner cable's length that is important, but it's length in relation to the length of its housing. The housing turns around corners and the inner works a shortcut on the corner insides. The housing has a plastic liner that eventually erodes, making the inner cable appear longer that it is supposed to be - to the "system" that is. In other words, your brakes require more travel to take or, your gears don't work as supposed to.

 

Further, dirt and eroded plastic makes the inner move with more friction, causing difficult gear shifts and on long rides, even tendonitis, if you are prone.

 

The practice of changing cables nilly-willy is one fuelled by greed.

 

However, you should change them if they don't move freely anymore. Only an experienced hand will know whether or not this is necessary. I say you should learn to assess your cable health for yourself.

 

Also, it makes sense to replace cables as a preventative measure. They do start to break inside the shifters due to sharp bends. If they break off, say in a Campy shifter, it is major surgery to remove it. If it breaks off in some STI shifters, it could mean a new shifter, as labour would cost a lot.

 

Healthy cables make your riding experience so much nicer.

 

Cables do not stretch or even settle in its windings. This is easy to prove since there is no lever on your bike or body long enough to take them into permanent stretch (yield). The science of winding cables has been perfected over the last 100 years and the windings are perfect, with no room for tightening.

 

Cables to avoid: Gore Ride On, Alligator and Jagwire coated cable and all other plastic coated cables. They're all rubbish and based on frying pan science.

Makes sense to me

[kosmonooit]

How much did they charge? its not a bad practice if is cheap enough to replace cables together housing but replacing the cassette with every service / change of chain is taking it to far and got me servicing my own bikes.

 

As mentioned what happens mainly with cables is corrosion of the outer, making them sluggish.

 

I must also beg to differ with JB of the Gore Ride-on system - they have Teflon type inners and are a sealed system (or supposed to be) - problem is with wet and dirt entering when end cap thingy fails, and its a goie weg situation.

Edited May 3, 2012 by kosmonooit

[RexFuzzle]

Just to clarify.. Cables do stretch... in certain cases, ie a mine, when the wheel stops at the top the people at the bottom are still moving and move by around 10m sometimes. This is a 2km cable though. In a bicycle I seriously doubt a little cable with a safety factor of around 6 is going to stretch... more likely, as has been said, housings wearing in.

As to friction... I don't get tired fingers from having to push the levers too hard so can't see any point.

My 2c

[kosmonooit]

And indeed if there is any 'stretch' why not just recalibrate the dérailleurs during the service? if not like the cables should become dysfunctional because its a mm or two change since the installation.

[Wallee]

...

As to friction... I don't get tired fingers from having to push the levers too hard so can't see any point.

My 2c

 

The problem comes when dirt gets inside the outer, and creates enough resistance that the derailleur spring doesn't have enough force to pull the cable back through the outer, resulting in sloppy shifting.

Edited May 3, 2012 by Wallee

[Minion]

Metal does stretch.

Although, he was right in the context of 'stretch' meaning something permanent. The incorrect use of the term bugs me, but I get what he was saying.

 

Teflon DOES reduce friction, FACT

Teflon DOES greatly improve shifting enough to justify the extra cost, MARKETING.

 

Another reason to change cables at the same time as the housing is if the ends become frayed. It's a serious mission to feed a frayed cable end through a housing without causing damage.

[Johan Bornman]

 

 

Teflon DOES reduce friction, FACT

 

Yes china, it is a fact which I never denied. My experience showed me that teflon isn't very durable and on cables it quickly peels off and jams the passage. Fact.

[TNT1]

- My experience showed -. Fact.

 

Don't you have to pick one or the other?

[Johan Bornman]

How much did they charge? its not a bad practice if is cheap enough to replace cables together housing but replacing the cassette with every service / change of chain is taking it to far and got me servicing my own bikes.

 

As mentioned what happens mainly with cables is corrosion of the outer, making them sluggish.

 

I must also beg to differ with JB of the Gore Ride-on system - they have Teflon type inners and are a sealed system (or supposed to be) - problem is with wet and dirt entering when end cap thingy fails, and its a goie weg situation.

How much did they charge? its not a bad practice if is cheap enough to replace cables together housing but replacing the cassette with every service / change of chain is taking it to far and got me servicing my own bikes.

 

As mentioned what happens mainly with cables is corrosion of the outer, making them sluggish.

 

I must also beg to differ with JB of the Gore Ride-on system - they have Teflon type inners and are a sealed system (or supposed to be) - problem is with wet and dirt entering when end cap thingy fails, and its a goie weg situation.

 

The Gore-TEx coating doesn't crumble like that on Jagwire, but it comes off in one piece. Often when you pull the cable out, a long stream of clear plastic that looks a bit like slime, comes out with it. The lengthwise tear seems to emanate at the turns in the cable where friction is higher. It chafes through and separates, jamming the casing.

 

In my experience, a standard stainless steel cable in a standard housing of good quality - Shimano, Giant, Unex, Campag etc, is the most durable. Whilst fluoride coatings like teflon undoubtedly are slick, the application is wrong. It works on pans, not in cables and car engines.

[Christopher Brunsdon]

Cables don't become longer. They may stretch elastically and if yoiu're on a long cable, like a tandem's rear brake, you can actually feel it. However, like an elastic band, they return to their original length as soon as you let go of the brake/gear lever.

...

 

Thanks JB for another classic post.

[Christopher Brunsdon]

Teflon DOES reduce friction, FACT

 

FACT continuous cable housing reduces the need for Teflon

[BLACKvoodoo]

Metal does stretch.

 

Take a piece of wire and bend it, it doesn't snap. The outside of that piece of wire is stretching, or getting longer. If it wasn't able to get longer, the wire would not bend.

 

You've got to compare apples with apples , Mild steel wire is hardly treated wire braid.... Would you buy your wife a glass wedding ring and call it a diamond??

[jannosmit]

I just replace mine once a year as good measure, R100 or less for 2m housing and 2gear cables. No funny business. I don't oil my cables, seems like the biggest mistake I made before.

[Minion]

You've got to compare apples with apples , Mild steel wire is hardly treated wire braid.... Would you buy your wife a glass wedding ring and call it a diamond??

The individual strands stretch, though. If they didn't stretch, the overall wire wouldn't stretch and return.

[rob!]

Yes china, it is a fact which I never denied. My experience showed me that teflon isn't very durable and on cables it quickly peels off and jams the passage. Fact.

 

Also Teflon tends to "rub off" quickly. Them cables are quite thin and there's a lot of pressure and friction on the thin edge so to say. Quickly the teflon is off and it's a normal stainless steel cable gliding over the metal inner side of the cable outer. Sadly the rubbed off teflon doesn't evaporate afterwards.

[Greg29]

Thanks all. OK, so it seems that the cable housing is more of an issue than the cable itself. Keep the housing clean and cable should be OK. I've also read that lubing the cable with a wax based chain lube also helps - haven't tried it yet myself.