Outer shifting cable liner - is there any benefit?

Discuss light weight issues concerning road bikes & parts.
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nemeseri
Posts: 787
Joined: Tue Apr 07, 2015 5:40 pm

by nemeseri

So I have a supersix and the shifting cables run under the downtube exposed to the elements. A shop recently replaced the housing and cables on my bike and they ended up covering the exposed cables with liners to "protect them from the rain and dirt". I was kind of surprised by this, but I don't really mind, it looks clean.

BUT then I was thinking and my question is that isn't there more cable friction with using liners? And at the end, is there any benefit at all?

by Weenie


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Calnago
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Joined: Sun Nov 07, 2010 9:14 pm

by Calnago

The liners aren't creating the friction in that application you describe, so I wouldn't have any worries about that. But I would rather the cables be exposed completely under the downtube as I think it looks cleaner than with liners around them the whole length. The place where you want the liner is to protect the cable (and possibly the frame) from rubbing against a hard and potentially rough (definitley adding friction) edge. I use thick walled PTFE for those "hard turns", and if the opening is exposed to dirt and grime from above, as it is when routing up to the front derailleur, I use a grub seal... ala...
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Remember the days when cables were free to just follow a smooth and direct path to their respective derailleurs, and just routed around a nice plastic cable guide? They worked, smoothly and effortlessy, and every now and then a good scrub with water underneath the Bottom Bracket to mostly unstick dried sports drink or whatever would make everything good as new. Nevermind... :)
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bm0p700f
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by bm0p700f

Exposed works fine. I have a number of bikes with exposed cables. In fact it's the bikes with internal routing that give me jip.

nemeseri
Posts: 787
Joined: Tue Apr 07, 2015 5:40 pm

by nemeseri

Calnago wrote:
Thu Jan 17, 2019 10:10 pm
The liners aren't creating the friction in that application you describe, so I wouldn't have any worries about that.
Thank you for taking the time to give me piece of mind and also the tip with the liners at sharp turns. Well, the mechanic used a black liner and the cables run exactly under the down tubes, so they are almost invisible because my bike is black... The bike shifts amazingly well after the housing / cable replacement and that might be partly because they are in the liner under the BB too... I hope they won't cause any headaches in the future.

Here is a picture:

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alcatraz
Posts: 2222
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Make sure you are using stainless steel cables.

I use some liner if the guide is wide enough to fit it. I don't want the cable to move around and possibly dig into the guide. It happened to me once on a soft guide. (I wouldn't use liner on external routing, would just preserve moisture.)

I'm also currently testing running some chain wax in all my housing, and because I wash my bike rarely I put liner with chain wax at the guide.

If it's good or not only time can tell.

So to summarize my experience: Stainless, very important. Low friction coating not important because it wears off. Try some wax chain lube, protect exposed areas with lining if you wash the bike rarely like me or worry about the chain guide. (for internally routed frames)

My tests are ongoing to increase cable service intervals. Someone else is probably further along in keeping cables running smooth for a long time so I'd keep an ear open.

The winner in my eyes is not the smoothest cable on a fresh install (which many people like to brag about, confuses the information out there). I'm after what stays the smoothest (or sufficiently smooth) after a few years of use.

TheKaiser
Posts: 643
Joined: Thu Sep 05, 2013 3:29 pm

by TheKaiser

Calnago wrote:
Thu Jan 17, 2019 10:10 pm
I use thick walled PTFE for those "hard turns", and if the opening is exposed to dirt and grime from above, as it is when routing up to the front derailleur, I use a grub seal...
Do you have a particular type/source you recomend for the PTFE tubing? Also, where do you source grub seals these days? When grub seals came out in the 90's with the peak in the Gore fully lined cable sets, and SRAM breaking into the shift/derailleur game, I'd thought they seemed like a great idea for all cable applications. Now, 20yrs later, they are few and far between. Those stupid accordian boots from V-brake cables are in plentiful supply, but they don't actually seal the end of the cable housing run the way a grub seal does, so they really just delay contamination a small percentage, rather than preventing it.

by Weenie


Jugi
Posts: 543
Joined: Sun Jun 24, 2018 8:10 am

by Jugi


nemeseri wrote:Well, the mechanic used a black liner and the cables run exactly under the down tubes, so they are almost invisible because my bike is black... The bike shifts amazingly well after the housing / cable replacement and that might be partly because they are in the liner under the BB too... I hope they won't cause any headaches in the future.
I'd say that is very good service from your shop but a bit overkill in this application. I have done the exact same thing on my wife's MTB, which goes through everything imageanable while commuting. I've tried to keep maintenance time on that particular bike at a minimum, and I'd say the liners definetly help in achieving that. MTBs should have full housings anyway.

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