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 Post subject: Cable outers
PostPosted: Wed Jan 07, 2009 8:40 am 
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Whats the difference in real world use between gear and brake cable outers? Can they be mixed and matched sucessfully? I know they're different sizes but how does this effect operation? Oh and if anyones got some spare white outers going cheap...... :roll:


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PostPosted: Wed Jan 07, 2009 8:53 am 
MacRetro rider
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BITD i mixed it up accidentally (i didn't know there was a difference back then) , used bits of brake cable for the gears and couldn't get them to index properly, as you probably know the gear cable has longnitudinal strands and the brake is spiral flat wire, i think the brake cable has a certain amount of give or springyness in it to provide modulation for the brakes, the gear outer has no give in it at all.

Dont know if using gear outer for the brakes would result in sharper brakes though, nver tried it.


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 Post subject:
PostPosted: Wed Jan 07, 2009 9:09 am 
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I bought a metre of this for the wife's stumpjumper just before Christmas, was nice and cheap but in my opinion not very good, Stiff as hell with no flex, a bitch to cut, and didn't seem very good quality for goodridge, And not spiral wound as mentioned above.

http://www.chainreactioncycles.com/Mode ... elID=23407


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 Post subject:
PostPosted: Wed Jan 07, 2009 9:34 am 
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Joined: Wed Jun 29, 2005 11:18 am
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Location: near cwmcarn
dont use gear outer for brake outer use. brake outer withstands much bigger compression force.


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 Post subject: Re: Cable outers
PostPosted: Wed Jan 07, 2009 10:23 am 
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kaiser wrote:
Whats the difference in real world use between gear and brake cable outers? Can they be mixed and matched sucessfully?

Modern (SIS) gear outers are designed to maintain a fixed length when they flex, but they won't withstand the high loads of braking. Brake outers are incompressible under braking loads, but don't keep a fixed length under flexing. So basically they're not interchangeable.

http://www.sheldonbrown.com/cables.html#housing

Some modern brake outers use an SIS-type design with an external Kevlar wrap to maintain the structure under braking loads. I guess you could probably use those for gears, but they're more expensive than SIS outers, so it wouldn't make a lot of sense.

Quote:
Oh and if anyones got some spare white outers going cheap...

Think I've got some white SIS outers somewhere...


Last edited by one-eyed_jim on Wed Jan 07, 2009 10:27 am, edited 2 times in total.

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 Post subject:
PostPosted: Wed Jan 07, 2009 10:24 am 
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Joined: Tue Oct 09, 2007 1:55 pm
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Location: New Forest, UK
Gear cable with longitudinal strands is critical to get indexing to work. However you cannot use it for brakes as it's too small inside to pass a brake cable through. Also, the higher forces with braking could burst the cable outer (you may have seen it happen occasionally with gear cables).


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 Post subject:
PostPosted: Wed Jan 07, 2009 10:37 am 
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The best and most affordable way to buy cable outers is to go to your LBS and ask them to cut you a specific amount (obviously you need to measure how much you want first!). :)

That way you aren't buying excess outer that you don't need and paying for packaging etc. I have always found that the large rolls of Shimano branded outer that bike shops use, works just as well as XTR in pre-cut packages. :)

Oh and as everyone else says, don't mix them up, I've seen some unpleasant crashes where gear outer has split when being used as brake outer.


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 Post subject:
PostPosted: Wed Jan 07, 2009 10:43 am 
retrobike rider / Gold Trader
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Location: In the Woods. . .
Yup all the above. Braking onuter in a helix is much more flexible too., not that flex is oftem a limiting factor any more. 'Rupture' load is much higher for helical brake outer, although as stated, marginally less dimensionally stable.


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 Post subject:
PostPosted: Wed Jan 07, 2009 10:51 am 
retrobike rider
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i use brake out for gears as well, as i find, (perhaps cuz i buy cheapy gear outers) that the strands get pulled through, so stick to brake outer for brake and gear, dont notice any difference in shift qaulity.


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 Post subject:
PostPosted: Wed Jan 07, 2009 1:21 pm 
Old School Grand Master

Joined: Wed Jun 29, 2005 11:18 am
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Location: near cwmcarn
BarneyRubble wrote:
The best and most affordable way to buy cable outers is to go to your LBS and ask them to cut you a specific amount (obviously you need to measure how much you want first!). :)

.


shimano 10M long roll of gear outer is like £7 trade..


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