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I'm currently putting a bike together with recycled parts and want to get away with not having to purchase a new gear wire. On my first attempt to thread the RD wire I ended up fraying it, cutting off too big a length and having to purchase a replacement. The old FD wire is too short so I want to switch the wire from the right to the left shifter.

New cables are cut and 'sealed' in a way that they're easy to thread.

For a used wire what is the best way to:

  • cut the wire to prevent fraying?
  • thread the wire through the cable outers and end caps without fraying?

It is relatively simple to thread the cable through the entry end cap and outer but even with removing the exit end cap it is difficult to thread through the last cap.

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I used to do what you are attempting. From sometimes painful and always frustrating experience, I have learned to just buy new inner cables. Also from experiance - cut the cable last - after the gears are working and shifting properly, cables in place and looking good. Nothing worse than deciding you don't like how things are threaded after you have trimmed the cable. –  mattnz Sep 2 '13 at 0:17
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One trick is to twist the cable slightly as you insert it into whatever you're inserting it into, taking care to twist in the direction that will "tighten" the cable. –  Daniel R Hicks Sep 2 '13 at 1:01
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If you don't have cable cutters, check your vice-grips (most people have these). Often there will be a cable cutter on the inner most part of the jaw. I find they do a great job of making a clean cut, as they generate a lot of force. A clean cut is required to reduce fraying. –  Kibbee Sep 2 '13 at 1:48
    
mattnz - I'm learning that but new wire is only $8 from LBS if I get it wrong, just thought I'd try this route first. Daniel - Thanks, I'll give that a go. –  DWGKNZ Sep 2 '13 at 23:53

3 Answers 3

up vote 4 down vote accepted

Before I purchased a cable cutter, I found the following method worked acceptably. After determining the cable length make a small mark with a permanent marker. Apply a small drop of superglue to the mark. After the glue dries, cut the cable with a pair of electricians pliers. The glue keeps the strands from unraveling. This still leaves the problem of cutting the outer cable housing cleanly. The pliers do not work to cut the housing. It gets crushed before it cuts. I used an air powered 3" cut off wheel. If you have to purchase either of these tools you are close if not above the cost of a Park Tool or other quality brand cable cutter. Some times the best tool for the job, is the right tool .

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Thanks I'll try the super glue trick, I've got a small amount of cable to play wiith in the length I need. Got many different kinds of pliers, tin snips and bolt cutters so will look for the pair that make the cleanest cut. –  DWGKNZ Sep 2 '13 at 23:51
    
Superglue can also help stop fraying if applied after cutting with proper cable cutters, or if your cutters crushed the cable in spite of gluing before. Solder works even better, but glue is simpler. Just make sure that if you twist any fraying back together with your fingers, do that before you glue :-) –  armb Sep 3 '13 at 12:39
    
When cutting the outer housing, have a bit of scrap cable inside it to reduce crushing. You can also clean up the housing end with a bench grinder to get a nice square end, removing any burr that did get crushed in (or, more slowly, with a file). –  armb Sep 3 '13 at 12:43

You just need a good cutter, to cut the cable - it must be strait at the end. Also get attention, that the wire is clean and perfect, have no flattened places, and isn't ripped in some place in the middle.
The outer also must be strait (usually you will want to cut the ends of the outer - they like to rip at ends). You also can feel it while inserting the wire into the outer, if it stuck in some place. On the outer ends (if cut) check, that the iron isn't bent inside, as it will impede the wire. Don't forget to oil the outer before inserting the wire.
This way you always can insert the old rear wire to forward gear or breaks.

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You usually do not need to oil the wire as most outer these days has a teflon-coated plastic sheath running through the centre. Oiling was necessary on older cable where the inner cable was in contact with the metal strands of the outer. –  harryg Sep 2 '13 at 11:02
    
Yet, if the outer is recycled, it can be unclean inside. So it's better to oil it even if it have teflon. And I would recommend not to use outer w/no teflon, as it get rusted shortly, and then you'll have to replace the wire again. –  Alexander Sep 2 '13 at 20:20

The method I've found that works best is:

  • clamp the cable tightly at the desired length with vise grips.

  • cut the cable as close to the vise grips with a sharp pair of wire cutters.

  • twist the wire back into shape with a small amount of sticky grease (to help it hold shape).

  • remove the cable outer end caps.

  • twist the wire (in direction of the wire grain) through the first end cap.

  • feed through the length of the cable outer.

  • hold the other end cap up to the light to align and twist as its fed through.

Also:

  • check for fraying and fix between each step

  • don't forget to put cable donuts on in the right place

  • $5 isn't much for replacement cables that don't fray!

Thanks for all your tips and help!

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