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I am a mtb rider and my bike has green/black theme going on. There are not many green (especially neon) sleved cables around. (Nor the heat shrinks' green match the bikes'). I do not want to interfere with the theme.

Based on that, I have 3 questions as follows;

The neon green on brake cables look so great that I want to use a new pair of them to power led's in the front. Would the metal's conductivity/resistance affect the power and generate an excessive power loss? Would the cable heat?

I do have a multimeter and I could measure the static resistance, Find the voltage and amp requirements of the lamp and assume the cable as a big resistor as shown:

schematic

simulate this circuit – Schematic created using CircuitLab

Would I need anything else to consider before hopping on to the project?

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  • \$\begingroup\$ How much current is needed and at what voltage? Does your brake wire have a conductive outer casing? Any shorts to the frame? And the resistance of the wire. All of these are needed to answer your question. \$\endgroup\$
    – Passerby
    May 14, 2021 at 0:01
  • \$\begingroup\$ There is no harm in measuring the resistance of the brake cable. Like passerby I expect it will be too high. But tail lights might be so low in power demand that you could get away with it. But no way can you power a headlight through stainless cable. This is just my gut reaction. It would be helpful to have real numbers. \$\endgroup\$
    – user57037
    May 14, 2021 at 0:40
  • \$\begingroup\$ Well I was thinking of powering Uv led's facing down my wheels (which in turn power up a neon/glow in the dark tape) for this I have not measured the cables yet but as far as I could see the UV led (single) could use up to a watt of power at 3xAA (4.5V). Assuming a handheld contains 9 serial led's, their draw would be 9W (unless limited by a resistor). Which I do think is too much for the brake cable \$\endgroup\$
    – ulasfo
    May 14, 2021 at 0:46
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    \$\begingroup\$ replace the brake line cable with copper wire \$\endgroup\$
    – jsotola
    May 14, 2021 at 1:04

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I should wait for the answers to the resistance measured and current needs but I believe its safe to assume a thin stainless steel braided cable of 4 feet is unlikely to support what you want to do. It has high resistance, aside from the issues about coatings or shorting to its case. Bowden cable is stainless steel cable in 2 or 3 layers meant for mechanical force not electrical properties. For any reasonable lighting needs it will just cause enough voltage drop to make it unusable but unlikely to get hot enough to be unsafe.

If you need a specific color cable and the brake cable's outside is what matches, then get regular wire (stranded more likely to last longer) and use the brake cable's sheath as a conduit.just cut the inner braided cable end off and pull it out. You can then thread the normal wire or wires in. You could also use the bike frame as a conductor but that involves tapping or sanding paint off and has some issues with material (carbon fiber is not going to work. Aluminum would be better etc).

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  • \$\begingroup\$ Running copper wire through the cable housings seems like a pretty good idea. \$\endgroup\$
    – user57037
    May 14, 2021 at 0:40
  • \$\begingroup\$ Could the housing be enough to protect unintentional shorts (like zaps)? and how do I calculate that? I assume I would need inner wire diameter, conductivity, watts passing through, the thickness of housing, and resistance of the housing? \$\endgroup\$
    – ulasfo
    May 14, 2021 at 0:53
  • \$\begingroup\$ Thats another concern. Since its made to move the inner cable the insulation is not tight and water and stuff can get in. Zaps depend on touching two conductors. And I'm suggesting using a normal insulated wire inside the housing of the brake cable so thats not an issue. \$\endgroup\$
    – Passerby
    May 14, 2021 at 1:21

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