Threading cables through the frame?

[Cyclopathic]

Before I start I wonder if anyone has any tips for threading cables back through the inside of the frame. It's a shopper style bike so has wide tubes which I'm hoping will make it easier.

It has struck me that if one replaces the outer and the inner cable one at a time you can use the one as a guide for the other. This is however moot as the cables are completely out. Is there a trick or is it a case of sticking either outer or inner through and hoping that you will be able somehow to wangle it through the hole at the other end?

 

[andrew_s]

As you've deduced, the correct technique is to use the old cable as a guide for the new - usually thread in a new inner, pull the old outer through leaving the inner behind, then slip the new outer over the inner.
Some frames have an internal steel or brass tube between the cable entry and exit points, which makes things very easy.

In the absence of either of these cases, there's no trick, and it's fiddly. I'd suggest starting with the inner, and trying to catch it at the exit hole with a small hook. You might like to visit your local sewing/haberdashery shop for a crochet hook.

 

[Number14]

Use a large blunt darning needle threaded with fishng wire in the hole. With a magnet, move the needle along the inside of the tube and you may be able to steer it out of the other hole. If you can't steer it out of the hole, move it past the hole and fish the wire out with a hook and then take the needle out. Then run the cable outer over the fishing wire, remove fishing wiee then thread cable through.

Fiddly but it works.

 

[Night Train]

As an electrician I am used to 'fishing' for cabled through very small holes.

I usually use a piece of rigid cable or wire, and straightened coat hanger would do, and then put a slight curve in it to match the entry exit points. Then mark the length of wire that is going to reach between the holes with a bit of tape or marker pen.
Feed the wire into one hole so that it curves towads the otehr hole.
When you have fed in up to the mark gently prod the wire in the direction of the exit hole and it should appear.

I have managed nearly 5' between holes in plasterboard this way and also around corners just by careful preshaping of the feed wire.

 

[wheres_my_beard]

I'm sure I saw a kit on Dragon's Den for electricians that could solve this problem. I've seen them in shops but can't remember what they are called.

It consists of a set of rods with magnets on the ends and some magnets to attach to the ends of the cable that needs routing. I suppose the actual problem of getting either the cable housing or the rod from hole A to hole B is still there but the rods may be more flexible or malleable to get the job done.

 

[Cyclopathic]

Thanks folks. As ever some useful ideas and things to think about.

 

[andrew_s]

Magnets won't work through a steel frame.
The whole frame gets weakly magnetised, so a needle or the cable will be weakly attracted to it, but the attraction is unrelated to where the magnets are on the outside so moving the magnet doesn't move the cable/needle.

You'd have to have the magnet on a thin screwdriver, then poke the screwdriver in the exit hole and hope the screwdriver was magnetised enough to catch the cable. I've just tried 4 stacked fridge magnets, a small electrical screwdriver and a brake cable. The screwdriver would catch the cable from about 8mm away, and hold on reasonably well once it caught.

A magnet on the end of a cable would just stick to the frame and stop you threading the cable.

 

[Sleeping Menace]

if you can find a length of cable liner, by that I mean the white teflon impregnated plastic stuff..which acts as a liner for some of the Clarks or Gore cables.. I forget which.. anyway.. start at one end with that.. feed it in wilst having the nozzle of your hoover against the opening where you want it to come out.. try to get as close to an air tight seal by wrapping your hand around it.. feed the liner in slowly.. after a bit.. you should hear one hell of a rattling noise.. means the liner has been sucked a little bit out the hole by the hoover..

now, that you got some liner all the way through correctly.. you can use that as a guide for your proper cabling...



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[screenman]

Bend a very this cable tie in half and poke the through the hole and keep pushing, this will open it up and fill the inside of the tube, push you cable through and when you feel there is enough in pull the cable tie out. Repeat until you have the desire result. Some tubes will have another tube inside. Failing that take them over the tubes and use clips.

 

[arallsopp]

You can get a long way with some button thread and a strong vacuum cleaner. I wired the dynamo hub to the lighting array of my 'bents using this technique. Here's what I did.

Feed button thread into whichever end won't fit neatly against the hoover attachment. Put hoover on other end and try to keep the gap between hose and frame reasonably sealed. Feed in more thread until you're pretty sure its been sucked out the other end. Tie cable to thread from whichever end you fancy, pull it through.

For extra points. Tie another bit of button thread on at the same time, and that way you can feed a second cable run along the same route should you need to. My furai now has tie off points at the boom, midships, rear stays and top of seat. My vacuum-fu is strong.

 

[ufkacbln]

Bend a very this cable tie in half and poke the through the hole and keep pushing, this will open it up and fill the inside of the tube, push you cable through and when you feel there is enough in pull the cable tie out. Repeat until you have the desire result. Some tubes will have another tube inside. Failing that take them over the tubes and use clips.

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