pstock

This has always baffled me.
many of the many bikes I have owned or worked.on have had the last 2mm of cable housing plastic removed to expose the wire strands.
I Find this so often that it seems to be a Beat Practice (though Leonard.Zinn is silent on the question)
On Bike Friday folding bikes in particular (where the cable goes slack when the bike is packed) this drives me NUTS.
The trimmed housing invariably falls out if the ferrule and then is often impossible to reinsert.

My various ferrules seem to fit my cable housings just fine without the trim back.

So what's the point? What I missing?





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Crankycrank

The housing shrinks over time. Although, I have seen some cut it back to fit in a ferrule but shouldn't have to do that.

mpetry912 

I suspect that somebody could not fit the jacketed housing into the ferrule.

with properly matched small parts this should not be a problem.

I have several little "goodie bags" filled stuff like this. The Weinmann 161 levers are VERY picky. Only the proper parts will fit.

/markp

Steve B.

Never done or heard of this. The housing and cable sets I buy come with end caps that fit over the housing, so no need to trim.

cyccommute 

They aren’t cut. The plastic sheath shrinks. I cut the cable housing myself in the picture below. The cable was cut blunt so that the sheathing ran all the way to the end. After a few months, the sheath had shrunk to what you see in the picture. The culprit is probably heat and the polyethylene of the plastic used. “Shrink” tubing is thinner polyethylene.

IMG_1362 by Stuart Black, on Flickr

KCT1986

What type of housing is this? Compressionless (linear) brake housing (seems that there is concentric rings showing in plastic)?

With linear strand housing, the outer plastic for shift or 'burstproof' layer for brake provides the support of the strands. Combined with the ferrules, it provides the structure that the linear strands need.

With standard coiled brake housing, it is sometimes necessary to cut back the plastic to fit in the frame/adjusters, Coiled housing is strong enough to handle this. Older brake tension adjusters was too small to fit some of the housing with the internal slick liners. Think Dia-compe.

FBinNY 

+1

It would be an extra step to cut housing this way, and I doubt anyone would bother.

In most production applications housing is cut with a spray cooled abrasive disc, producing a perfectly square end that you can't duplicate with a cable cutter.

So, I also chalk it up to shrinkage, though I suspect is purely a result of aging.

One way you might confirm is by looking at the fit to the ferrule. These are carefully chosen for a snug, supportive fit. So, the ferrule would match the housing in either the stripped or covered diameter.

pstock

compressionless.
shifter housing.
and someone had to work hard to remove just the plastic outer shell and not cut the wire strands. It's not just an accident.
I've encountered this dozens of times. (and I remember each instance because unless/until I can stuff those 12 strands of wire back into the ferrule the bike is unusable).

I cannot figure it out.
but unless someone can tell me I am really missing something, I am ready to move on and just chop off the loose wire strands and reinstall.

pstock

Wait!
do you think the plastic housing shrank leaving the wire strands exposed? and it wasn't cut back deliberately?
No Way! that seems incredible

(though yes, the busted up ferrule is a classic of mashed up housing/ferrule / seat fittings.

Peter

FBinNY 

Yes, that's what I suspect. I know that the cover material is prone to shrinkage, and I can't see a reason for anyone to make the effort to strip the housing.

So, the "incredible" is more credible than the alternatives.

Homebrew01

Merged duplicate threads

well biked

If you recable ten bikes that have extensive usage since the last time new cables were installed, I'd estimate at least six or seven of them will have shift cable housing that looks like this to some degree as you remove it. Very, very common. As others have mentioned, heat, the makeup of the housing are likely causes, and I also think the cable housing being put under some stress from usage all play a part.

cyccommute 

It has nothing to do with the ferrule. I’ve seen it with plastic ferrules and with metal ferrules. It’s strictly a function of the polymer used for the plastic sheathing. You can trim back the exposed wires without issue if you don’t shorten cable housing too much. It won’t shrink further.

maddog34

cut a housing with a high speed disc cutoff wheel some time.. the plastic melts back away from the heat, then must be trimmed to fit an end cap over it.

when cutting HUNDREDS of cable housings at once, a stop is set to the correct length, then a Cutoff/Chop Saw with a Thin grinder disc is used to quickly sever the housings at that pre-set length... a wire stripper is then used to strip away the melted plastic..........

and i totally agree that the stranded housings done this way are a problem.

pstock

Mystery solved. Who knew!?
I can sleep again.
thanks all.

KCT1986

Interesting that the casing retracted that much. Maybe lower quality housing? Or the extreme heat/cold cycles in the area?

Are all the housing ends on this bike the same?

Iride01 

On one bike I didn't have a metal ferrule the proper size to fit the cable. So I had to trim back the coating. So maybe you got that bike I'd gotten rid of that I'd done that to. But it was a red bike, not yellow. As others say, that coating does shrink a lot more than you'd expect over time.