PDA

View Full Version : Shrinkage

gdw
08-20-2008, 05:45 PM
What's up with the smaller diameter Shimano shifter cable housings? A number of the bikes that I've worked on this summer, built by some of the better local shops, have had housings where the outer plastic sheath shrank and exposed the inner steel wires (see the attached picture). The owners reported that their bikes worked great for a few months and then shifting became unreliable. The exposed wires were the problem and caused the cables to bind at the ferrule entrance. The housings were the correct length and seemed to be cleanly cut. This has occurred on both road and mountain bikes and with the generic black housings as well as top of the line Dura Ace version. I expect that it is caused by the repeated flexing of the housing but find it odd that it becomes an issue with such little use. Anyone else experiencing similar problems?
ergott
08-20-2008, 06:15 PM
I've had similar results. I'd like to know the deal-io as well.
Chris
08-20-2008, 06:27 PM
+2. Thought it was just me.
jmc22
08-20-2008, 07:05 PM
Maybe we should ask George Costanza, he knows about shrinkage.
PaulE
08-20-2008, 07:43 PM
That pool water was cold! Maybe a nice lobster omlette will even things out.
Mike748
08-20-2008, 07:50 PM
Same here and pretty quickly on the silver DA cables. Also noticed the outer jacket cracking.
dookie
08-20-2008, 09:27 PM
same deal here...with (gasp!) genuine campy housing.
jbl
08-20-2008, 10:41 PM
same deal here...with (gasp!) genuine campy housing.

+1, but it took a year before I noticed any funny business.
BdaGhisallo
08-21-2008, 02:40 AM
You're right. The repeated flexing but moreso the force exerted on the housing by the shifting, forces those inner wires out. The secret is metal, crimpable ferrules. I have posted on this a few times:

I get the cnc crimpable ferrules from biketoolsetc.com and I crimp them. They may not need it, but crimping them makes sure that they go nowhere! And I have been using 5mm shift housing with my STI for the last few years. It's much stiffer and allows for a better shift, imo.

I use this special crimping tool. It does 4mm right through 6mm, including inner cable tips, IIRC. It crimps 360 deg around the ferrule. It's nice! It ain't cheap, but it is worth it since it will last forever.

http://www.biketoolsetc.com/index.c...&item_id=LY-T08

You will have zero problems if you go this route.
Geoff