Originally Posted by Plantmiester
The openings don't seem wide enough to allow a second cable attached to the initial to be pulled through, so I am at a complete loss as to how to solve this.
I've had to do this on my S-Works Transition frame. It is a little tricky.
I hope that you have a Carbon or Al frame - Its Aluminium, right?
The hole should be wide enough to fit a needle and thread or a 25mm nail with thread attached.
The thread should be a good 5 foot long so that you can pass it
Tie the other end of the thread to the end of the cable that you want to pass through. Use a fishing knot to tie it on.
Drop the Needle/Nail into the hole and use a magnet to move the thread along. (A spoke magnet works well).
Gently push the cable through and use the thread to guide it.
I'd use an old cable to practice. It takes a bit of time to do it in the first place, but once you get the hang its fine.