Shift cable stuck in a bad place

Discuss light weight issues concerning road bikes & parts.
justinn
Posts: 40
Joined: Sat May 04, 2013 5:34 am

by justinn

Well, I messed up. I have a Scott Foil R2 (integrated cables) and I was feeding a shift cable in backwards through the chainstay to get it to pop out near the bottom bracket where I would tape it to the knew shift cable and pull it back through.

However, I thought I had more line than I really did and ended up pulling it (pretty hard) to the point where the cylindrical head was stuck about an inch and a half in. I can't get much tension in the line to push it back out because the chainstay is so long that the cable folds in on itself before the cable head moves at all.

I've tried using a really small amount of contact adhesive to stick an allen wrench to it but that failed (I'm really hoping the adhesive didn't bulge out and seal in the cable). My next thought it using really strong epoxy (JB Weld) to stick a small cable to it and pulling it out - at this point I'm sure it's pretty well lodged in there.

Any ideas better ideas?

sungod
Posts: 1537
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

perhaps you can use a dremel with a small drill bit to put a hole in the end, then thread a screw in and use that to pull it out

start with a small bit that won't skip as much/far to make a pilot hole, then enlarge it to a size that'll take the screw

or...

if there's room, get a piece of stiff wire and try poking it in from the bb end to push the head out

freezer spray - but check first to make sure steel coefficient of expansion is greater than cf+epoxy

is the area the head is lodged in structural or a separate guide channel, if it's the latter you may be able to get a dental pick in there and gradually ease the head out

hope you find a good solution!

justinn
Posts: 40
Joined: Sat May 04, 2013 5:34 am

by justinn

dremel may eventually be the way to go

The smart thing to do would have been to use cable housing and put the opposite end of the shift cable through that and thread it through to where the wire is stuck. There would have been more than enough force there to push it back through. Of course I didn't think of that until after I'd tried contact adhesive and lodged it further up the tube. Really really hoping I didn't bond it to the frame.

At this point a dental pick wouldn't work either, I filled the hole with water and nothing goes through so it's a pretty tight seal...

sungod
Posts: 1537
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

didn't think of cable housing, that certainly sounds the best way

put a bit of the glue on bit of metal foil, let it dry, see if white spirit dissolves it, for contact adhesive o think it will, if it does then put a few drops onto the stuck head let it seep in (it's also slightly lubricating until it evaporates) for 15-20 minutes, re-applying if it dries, then try using the outer to shove it out

white spirit is ok on carbon rims, so should be ok on a cf frame

pawnii
Posts: 359
Joined: Sun Sep 27, 2009 9:54 am
Location: Australia

by pawnii

can u get an old wire coat hanger in the BB end of the chainstay?

you can also try to heat the inside of the chainstay to loosen the adhesive. Contact adhesive fails under heat.
Either with a heat gun or soldering iron or something.

If you had a soldering iron with a long tip (2inchs) you could heat the wire directly to melt the adhesive.
2012 Scott Foil Premium

justinn
Posts: 40
Joined: Sat May 04, 2013 5:34 am

by justinn

Could I solder a wire or something to the end of the shift cable? I was thinking of going out and getting some JB Weld to bond a small allen key to it, but that again runs the risk of bonding it to the frame as well and that'd be game over. I'll head out and see if I can find a long enough tipped soldering iron here locally and give that a shot I hear WB-40 also helps to break down contact adhesive? I'll either try that or some white spirit if I can find it

justinn
Posts: 40
Joined: Sat May 04, 2013 5:34 am

by justinn

aaaand now that the suns up, I can see the situation a little better. Looks like the super glue adhesive did a nice job of filling in around the shifter head. Effectively sealing it in.

I'm looking into soldering irons, but having a hard time finding anything long enough (2 inches at least?). Acetone will dissolve super glue, but also the epoxy that holds carbon fiber together.

Does anyone know a carbon fiber safe super glue solvent?

It may be dremel time soon.

Tenlegs
Posts: 285
Joined: Wed Jul 16, 2008 10:37 am

by Tenlegs

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Last edited by Tenlegs on Sun Jun 16, 2013 6:08 am, edited 1 time in total.

justinn
Posts: 40
Joined: Sat May 04, 2013 5:34 am

by justinn

That's an awesome idea, my concern would be adding tension to the cable effectively lodging it deeper in the frame though? I'm pretty sure that the super glue is pretty well set up locking in the shift cable... I have access to liquid nitrogen and I'm thinking about freezing the super glue to get it to crack?

I now know that carbon fiber has a negative thermal expansion coefficient - so heating it would make it shrink (which would be ideal as it would make the hole minutely bigger, loosen up the superglue) but might make the steel expand to a greater degree??

Tenlegs
Posts: 285
Joined: Wed Jul 16, 2008 10:37 am

by Tenlegs

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Last edited by Tenlegs on Sun Jun 16, 2013 6:07 am, edited 1 time in total.

justinn
Posts: 40
Joined: Sat May 04, 2013 5:34 am

by justinn

by turning it won't that pull on the cable though?

sungod
Posts: 1537
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

ah, at first you said contact adhesive

if you actually used superglue, acetone is the solvent to use, it will attack the bond and then you can use the cable outer to push it out from the other end

justinn
Posts: 40
Joined: Sat May 04, 2013 5:34 am

by justinn

http://www.lifeandhome.com/welder-73065 ... QgodlQMAZw

that is what I used, I'm not sure what it is

Dremeling is much harder than I thought it would be, probably making it worse. I'm going to call a local carbon repair shop on Monday

pawnii
Posts: 359
Joined: Sun Sep 27, 2009 9:54 am
Location: Australia

by pawnii

I'm looking into soldering irons, but having a hard time finding anything long enough (2 inches at least?)


use a nail that's the same diameter as your soldering iron tip.
2012 Scott Foil Premium

justinn
Posts: 40
Joined: Sat May 04, 2013 5:34 am

by justinn

I have no experience with soldering and would probably mess it up further, I'm calling a local carbon repair shop on Monday

Unless there's anyone here in Seattle that knows how to solder?! haha ohhhh what a weekend

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