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Cable tunnels crumbling - how long does it have to live

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Cable tunnels crumbling - how long does it have to live

Old 07-19-20, 01:11 PM
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btppberk
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Cable tunnels crumbling - how long does it have to live

Last summer I had to get my 2012 Focus carbon fiber brake cable replaced. The mechanic said the tunnels taking the brake cable were crumbling (!) and he wasn't sure he'd be able to get the cable through. (Unfortunately the warrany was one or two years.) He eventually succeeded, but now I am wondering how many years the bike has left. I'd like to get a power meter and new wheels, but not if the bike's end is in sight.
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Old 07-19-20, 01:34 PM
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Wheels, cranks, power meters, etc to a large extent will be able to be moved to a new bike, unless you jump to a different technology (disc brakes, thru axles, BB30, etc).

My guess is that where there is a will, there is a way. To a large extent brake cable housing can be replaced with full-length housing, and either larger holes drilled in the frame, or attach with tie-wraps.

Shift Cable housing can be a little more problematic.
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Old 07-19-20, 01:42 PM
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As per Clifford: full length housing either externally ziptied to the top tube or by cautious enlargement, if needed, of the
top tube openings to allow full length housing to be routed internally. Top tube strength and the forces applied to it in
normal riding mean that enlarging the openings would not compromise the tube. If there is a full length internal guide
tube for the cable this would have to be removed or shunted aside. Many disc brake cross/gravel bikes use full
length external housing for the cable pull rear disc.
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Old 07-19-20, 02:06 PM
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Thanks for the info. I never even thought about those options--and the mechanic hadn't mentioned them either. I appreciate the feedback.

One last question: does crumbling housing imply that the frame in general is deteriorating such that need to worry about my safety? Thanks again.
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Old 07-19-20, 02:29 PM
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Is there any way you can upload some photos showing the issue? Perhaps a better description of what is deteriorating? Other problem spots? Deterioration around dropouts?

Perhaps some aluminum corroding somewhere?

There is a lot of debate about the longevity of Carbon Fiber frames.

There are many carbon fiber frames > 20 years old still on the road, but perhaps not getting hammered with a lot of hard miles every year.

Most pro racers retire their bikes after a couple of years. Sometimes they get sold for a "second life". Still, tens of thousands of miles of high power riding every year can be hard on a bike.

On the other hand, a casual weekend rides, and the bike could last quite some time.

How many miles do you do? What type of riding? Racing? Crashing?
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Old 07-19-20, 02:39 PM
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The problem was apparently somewhere inside the tunnel that runs through the top tube. You can't see it from the outside, the ports where the bike cable comes out looks entirely fine. Everything else on the bike looks fine to my eye too, including the dropouts, which show some erosion of the paint, but not the frame itself. No crashes. I wouldn't think twice about the health of the frame until the mechanic told me he may not be able to fix the brakes.

The bike got about 3 years of ~150 miles / week before a job ruined everything, relegating it mostly to summer interval work.
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Old 07-19-20, 03:39 PM
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The only thing that tunnel provides is easier cable replacement since it guides the cable and/or housing as you feed it through. If it's damaged, you get around this by tying a string to the old cable end before you remove it and then using the string to pull the new cable back through. I'm not at all a fan of internal cable routing but I've dealt with them in the past on a couple of older Trek frames and the string method always works for either cable housing or inner wires.
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Old 07-19-20, 08:25 PM
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The bike is only 8 years old and the CF cable tunnels are crumbling?

Can I give you a word of advice? Stay away from buying another Focus bike!! Actually consider staying away from CF bikes as well, maybe get a titanium bike instead...

20 year old and older CF bikes were using thicker CF walls, but nowadays they are going thinner and thinner in the pursuit of weight competition, and in that pursuit you will have a shorter life expectancy for a CF frame. Those lightweight CF frames are great if you have sponsor who throws new bikes at you every season for free.

Crap, I gotta run, I see a mob of angry people running at me with CF forks to stab me with, but I have a steel fork to fight them off with; here is one war I saw between CF and steel forks: https://vimeo.com/106021360
So I have feeling I'll win the war.
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Old 07-19-20, 08:37 PM
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I hear what you are saying about Focus. But I think some companies, including Trek and Specialized, warranty their frames from defects for life.
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