How necessary is it to replace cable sheaths?
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How necessary is it to replace cable sheaths?
All,
I am contemplating replacing the cables on my bike - brake and shifter cables. They are actually the original cables - from 2014.
How necessary is it to replace the sheaths? or can I get by with replacing just the cable inside? Could I just spray down new cables with lube in the existing sheaths? Or is that really a bad idea?
The shifter cables are fraying a bit at the shifters so I figure its a good idea to replace them before my trek.
I am contemplating replacing the cables on my bike - brake and shifter cables. They are actually the original cables - from 2014.
How necessary is it to replace the sheaths? or can I get by with replacing just the cable inside? Could I just spray down new cables with lube in the existing sheaths? Or is that really a bad idea?
The shifter cables are fraying a bit at the shifters so I figure its a good idea to replace them before my trek.
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If your shifting is working proper, then cable replacement is all you need.
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Yep. Everything works fine. Of course, things have been tuned and adjusted numerous times but that is just normal maintenance. No sticking cables.
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You got 6 years out of them, replace both housing and cable. A nice fresh start to possibly 6 more years. You have beat all the odds unless you ride very little.
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Housing not 'sheath'. This is where all of the wear takes place (excepting cables fraying inside shifters) so you should always replace the housing. Think about it...the fairly smooth steel cable runs inside a plastic lined housing. Where do you think the wear is going to occur? If you're guessing the housing you're correct.
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You'll probably be pleased with the extra work and cost if you replace the housings. Mine was only four years old when I replaced cables, and the old housings were definitely reducing the shifting performance.
I'll often clean and lube cables on an old cheap bike to get it running again for someone who can't afford proper service.
I'll often clean and lube cables on an old cheap bike to get it running again for someone who can't afford proper service.
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Housing not 'sheath'. This is where all of the wear takes place (excepting cables fraying inside shifters) so you should always replace the housing. Think about it...the fairly smooth steel cable runs inside a plastic lined housing. Where do you think the wear is going to occur? If you're guessing the housing you're correct.
It’s a shame that the OP is replacing cables just because the ends have frayed, (although at 6 years it’s better to start a long trip with new cables.). Using end caps would have allowed the old cables to be saved as spares.
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True, but the plastic liner wears away only until it wears through, and the cable is now rubbing against the steel helix of the housing, like before lined housing was a thing. If this introduces too much friction, especially with fragments and shreds of liner floating around in there, it will show in the shifting and then that section of housing can be replaced. The section carrying the big bend of cable to the rear derailer is likely the only section that will likely need replacing and is the easiest to replace, not being under tape. But if shifting is fine, why replace any housing?
It’s a shame that the OP is replacing cables just because the ends have frayed, (although at 6 years it’s better to start a long trip with new cables.). Using end caps would have allowed the old cables to be saved as spares.
It’s a shame that the OP is replacing cables just because the ends have frayed, (although at 6 years it’s better to start a long trip with new cables.). Using end caps would have allowed the old cables to be saved as spares.
Ever heard of 'preventative' maintenance? Service instead of repair?
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And shifter cables aren’t don’t have helixes in them. They are rods of metal which would wear even less than a helix would.
Hardly a valid comparison. A worn cable housing won’t cause a catastrophic and highly expensive repair. The broken cable at the shifter will and the cable needs to be replaced before another shift because a broken cable in a shifter may destroy the shifter.
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That’s the silliest comparison I’ve ever heard, unless your business relies on selling cable housing (which for all I know it may, so fair enough.). Of course I change my oil and timing belt and do other service stuff on my car, but I don’t change the piston rings just because the car is 20 years old (really) and they’ve never been changed.
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Read KC8QVO’s original post. The cables aren’t fraying at the derailer end but at the shifter end. A very different...and potentially much more expensive....problem.
And shifter cables aren’t don’t have helixes in them. They are rods of metal which would wear even less than a helix would.
Hardly a valid comparison. A worn cable housing won’t cause a catastrophic and highly expensive repair. The broken cable at the shifter will and the cable needs to be replaced before another shift because a broken cable in a shifter may destroy the shifter.
And shifter cables aren’t don’t have helixes in them. They are rods of metal which would wear even less than a helix would.
Hardly a valid comparison. A worn cable housing won’t cause a catastrophic and highly expensive repair. The broken cable at the shifter will and the cable needs to be replaced before another shift because a broken cable in a shifter may destroy the shifter.
My understanding of modern derailer housing is that the longitudinal rods/wires have (or had) a slight twist in them, like the rifling lands in a firearm, or like the protein chains in collagen. So this makes them helices too. Gives them more resistance to being spread apart by the light forces involved in shifting. Brake housing has to be different. Calling them all helices allowed the same word to apply also to old-fashioned housing which was a tightly wound helix (and unlined BITD.)
Suggestion: Don’t tell people to “Read xxxx”. All it does is express hostility, which puts your blood pressure up a bit and makes you have a stroke sooner. You are accusing the person of not reading something (as in not preparing for a class or business meeting) instead of allowing that a point was mis-read, as we all have done, including those who get one-up by throwing rocks. Of course I read the post. How would I know what the post was about if I hadn’t?
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‘Kay, didn’t catch that. I read “shifter” as “derailer”. My bad. Absolutely replace cables at once if any “fraying” at the shifter — broken strands, really. Beauty of cable splicers as used on take-apart bikes is that it’s easy to release the cable at the splicer and back it out of the shifter to check for the kinks which will become broken strands soon. If all is well you just screw the splicer back together with no readjustment.
My understanding of modern derailer housing is that the longitudinal rods/wires have (or had) a slight twist in them, like the rifling lands in a firearm, or like the protein chains in collagen. So this makes them helices too. Gives them more resistance to being spread apart by the light forces involved in shifting. Brake housing has to be different. Calling them all helices allowed the same word to apply also to old-fashioned housing which was a tightly wound helix (and unlined BITD.)
Suggestion: Don’t tell people to “Read xxxx”. All it does is express hostility, which puts your blood pressure up a bit and makes you have a stroke sooner. You are accusing the person of not reading something (as in not preparing for a class or business meeting) instead of allowing that a point was mis-read, as we all have done, including those who get one-up by throwing rocks. Of course I read the post. How would I know what the post was about if I hadn’t?
My understanding of modern derailer housing is that the longitudinal rods/wires have (or had) a slight twist in them, like the rifling lands in a firearm, or like the protein chains in collagen. So this makes them helices too. Gives them more resistance to being spread apart by the light forces involved in shifting. Brake housing has to be different. Calling them all helices allowed the same word to apply also to old-fashioned housing which was a tightly wound helix (and unlined BITD.)
Suggestion: Don’t tell people to “Read xxxx”. All it does is express hostility, which puts your blood pressure up a bit and makes you have a stroke sooner. You are accusing the person of not reading something (as in not preparing for a class or business meeting) instead of allowing that a point was mis-read, as we all have done, including those who get one-up by throwing rocks. Of course I read the post. How would I know what the post was about if I hadn’t?
The outer housing has only a very slight twist if it has any at all. It’s certainly not tight enough to cause the cable, which has its own twist, to rub on the rods and cause much harm to either the cable or housing. Brake housing’s helix is at almost 90° to the cable.
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Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
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Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Last edited by cyccommute; 10-11-20 at 06:08 PM.
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If it's a Shimano bike with 2nd-gen 10s (the first with under-tape cables) replace the housing. Low signal to noise in that system, you need all the help you can get.
The liners don't need to wear through before they cause more friction. And use die-drawn cable.
The liners don't need to wear through before they cause more friction. And use die-drawn cable.
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Suggestion: Don’t tell people to “Read xxxx”. All it does is express hostility, which puts your blood pressure up a bit and makes you have a stroke sooner. You are accusing the person of not reading something (as in not preparing for a class or business meeting) instead of allowing that a point was mis-read, as we all have done, including those who get one-up by throwing rocks. Of course I read the post. How would I know what the post was about if I hadn’t?
^This^ exactly.
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#20
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My bike is a 2008, 10 speed 105/ Ultegra mix. Shifters are 105, last generation before the shift cables went under the bar tape.
Brakes - I replaced cables and housing in early 2018, just because they are brakes. AFAIK they were original. Cables looked perfect, there was no significant friction, brakes worked great.
Rear derailleur. I have to replace the cable every 7,000 miles, it begins to fray in the shifter. I replace the rear housing loop at the derailleur every time as that’s where I find friction develops. Last time I changed the cable I did not have any housing, so I didn’t change it. I’m about due to replace both again. I’m getting some friction and slightly slow shifting down the cassette now with about 13,000 miles on the housing. I normally change the shifter to frame housing every other cable change.
Front derailleur, I changed both in 2018, AFAIK they were original (bought the bike used). There was lots of friction in the shifter-to-frame housing, so much I was surprised it shifted at all. So 10 years was too long.
YMMV
Brakes - I replaced cables and housing in early 2018, just because they are brakes. AFAIK they were original. Cables looked perfect, there was no significant friction, brakes worked great.
Rear derailleur. I have to replace the cable every 7,000 miles, it begins to fray in the shifter. I replace the rear housing loop at the derailleur every time as that’s where I find friction develops. Last time I changed the cable I did not have any housing, so I didn’t change it. I’m about due to replace both again. I’m getting some friction and slightly slow shifting down the cassette now with about 13,000 miles on the housing. I normally change the shifter to frame housing every other cable change.
Front derailleur, I changed both in 2018, AFAIK they were original (bought the bike used). There was lots of friction in the shifter-to-frame housing, so much I was surprised it shifted at all. So 10 years was too long.
YMMV
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Read KC8QVO’s original post. The cables aren’t fraying at the derailer end but at the shifter end. A very different...and potentially much more expensive....problem.
And shifter cables aren’t don’t have helixes in them. They are rods of metal which would wear even less than a helix would.
Hardly a valid comparison. A worn cable housing won’t cause a catastrophic and highly expensive repair. The broken cable at the shifter will and the cable needs to be replaced before another shift because a broken cable in a shifter may destroy the shifter.
And shifter cables aren’t don’t have helixes in them. They are rods of metal which would wear even less than a helix would.
Hardly a valid comparison. A worn cable housing won’t cause a catastrophic and highly expensive repair. The broken cable at the shifter will and the cable needs to be replaced before another shift because a broken cable in a shifter may destroy the shifter.
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Brake housing can last a decade before the plastic cracks from sun exposure.
Derailleur shift cables fail due to fatigue bending around the shift drum which is smaller than mechanical engineering guidelines require for wire rope. Life is halved with cables routed under the bar tape having hoods level with the tops due to the added tight 90 degree bend. Life in miles depends on how often you shift.
Lined rear derailleur housing has less life than two inner cables so it's better to replace it at the same time. The cables cut a groove in the lining which pinches them increasing friction. Rear derailleur loops also gunk up from road dirt. I break rear shift cables in 2200-2500 miles in good shape shifting like I have ADHD, and half that in bad. Other people get up to 20,000 miles.
Front derailleur cable and housing last a long time. My last two replacements were at 17,000 and 11,000 miles due to the housing friction increasing.
YMMV. Track how much life you get and replace your cables sooner to avoid unpleasant surprises.
or can I get by with replacing just the cable inside? Could I just spray down new cables with lube in the existing sheaths? Or is that really a bad idea?
The shifter cables are fraying a bit at the shifters so I figure its a good idea to replace them before my trek.
Last edited by Drew Eckhardt; 10-15-20 at 03:03 PM.
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#23
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Will you have to replace the bar tape?
Do you want too?
If not put new cables in it and see how it goes.
The old outer won't wear out the new cable.
It can be done anytime and you already know how to do it.
Do you want too?
If not put new cables in it and see how it goes.
The old outer won't wear out the new cable.
It can be done anytime and you already know how to do it.
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She always asks for a new sheath, but, sometimes, I go two-fer.
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Thanks for the replies.
I replaced just the cables, for what it is worth.
And yes - the rear shifter cable is the one that was frayed at the shifter. Oddly enough, that was the only "bad" cable of the 4 (2x brake, 2x shifter). However, having replaced all 4 that makes me pretty confident in their service.
When I put the new cables in I added TriFlow lube to them. None of the cable runs were sticky. The rear brake was the only one that was stiffer and that is because it is a solid housing all the way to the rear dropout. All the other housings are much much shorter (shifters are only from the bar to the down tube and the rear has the curve at the rear, the front is only the bar to the down tube).
So for now, and until something else comes up in performance issues, I am fine with the new cables only.
I replaced just the cables, for what it is worth.
And yes - the rear shifter cable is the one that was frayed at the shifter. Oddly enough, that was the only "bad" cable of the 4 (2x brake, 2x shifter). However, having replaced all 4 that makes me pretty confident in their service.
When I put the new cables in I added TriFlow lube to them. None of the cable runs were sticky. The rear brake was the only one that was stiffer and that is because it is a solid housing all the way to the rear dropout. All the other housings are much much shorter (shifters are only from the bar to the down tube and the rear has the curve at the rear, the front is only the bar to the down tube).
So for now, and until something else comes up in performance issues, I am fine with the new cables only.