A new answer to an old question - I now use a normal soldering iron and some flux and solder. It takes a fair amount of heat, but a dab of solder on the cut end means the strands will never unravel, and it makes the new wire easier to thread too.
For me, the crimp-on caps fall off on the first ride, and anything else just looks wrong.
Downside - the ends can still be pokey, and can put a hole in your skin easier than if the end is capped.
This works less-well with old greased up cables, I have used a blowtorch to burn them clean, then apply flux.
Of course, this depends on having the strands laid. Consider a new cable, solder it, then fit.