Here is what I want to do. I want to cut the wires on a bike computer. I want to do this so that I can run the wires through the inside of my frame instead of having them wrap around the downtube of the frame. Then, I want to reattach the wires. Basically, I want to route the bike computers internally.
Has anyone done anything like this before? Any tips on how to get this to work correctly?
Tried it once, and wouldn’t try it again. The wires are reinforced with strands of nylon or polyester spun in there with the copper strands. When you try to solder the wire, the melted synthetic forms an insulator. Had a hell of a time trying to get a workable connection, even after trying to tease out all of the synthetic strands from the copper. I finally got it to work (after so many attempts that I was close to running out of wire), but when that harness got damaged in the Great Crash of '07, I opted not to attempt it again.
Crimped butt joiners don’t work, either.
Zip ties are very effective at securing wires to the frame, and most hardware stores carry electrical tape in a wide variety of colors. Anyway, I plan to tell everybody that the drag penalty from the wires is the major reason why I’m not placing in most of my races.
i did this with my SRM PCV cable, its really easy, the hardest cut is the first one. You are going to need a solder gun and shrink wrap and a heat gun.
make sure you don’t get the wires too hot and burn them. other than that its just a straight forward solder job.
good luck!
I’ve done a couple of times on mine and my partners plasmas. The hardest but for me was threading the wires down the down tube. I presume you’re using a computer with cadence and possibly a rear wheel speed sensor?
Cut the reed switches off, but don’t strip any wire ends till after you’ve threaded them through the downtube. I used a long gas welding rod to draw the wire through the gear cable entry and through the opening at the BB. your mileage may vary depending on your bike.
each wire ( cadence and speed ) will have two inner wires, one with a coloured cover, the other no cover. they help when you rejoin the sensors ( in theory any sensor will work in any position, so long as its on the correct wire to the base unit for the job its doing )
When you cut the wires, leave a bit of length for fine tuning the position, ( my bike is large, so needed all the wire, my GF’s is XS and I was able to trim a big chunk out ) don’t be tempted to trim them tight, cable tie or tape the slack somewhere out of the way.
If you can’t solder, learn, and use heat shrink tubing as well, 2 pieces minimum, one over the coloured wire, and another over the whole join for maximum reliability. the wires are almost always colour coded, so mixing them up shouldn’t be too much of a problem.
I have done this several times with my wired powertap. I drilled a small hole right next to the front derailleur housing stop on the downtube of my P2K, fortunately my Slice has an additional opening where the cable goes into the downtube for a wired SRM so no drilling required. 
I split the outer insulation on either side of the cut, strip the inner wire using my fingernails and slide a length of heat shrink tubing over the outer and move it well out of the way so the soldering heat doesnt affect it. I twist the small inner wires together and solder them, and insulate them with a small piece of electrical tape that just wraps them. Then I slide the heat shrink tubing down over the joined area and err shrink it. I have had zero issues. Its a lot neater than zip ties and tape. Wireless would be nice, but I have two powertaps and the cost of converting them to wireless is not in the budget.
Kevin