Okay, you're out on tour, 50 miles from the nearest bike shop and you snap a shift or brake cable. You have a lot of up and down ahead so riding single speed or without both sets of brakes is not a viable or safe option. You pull out your spare cable (you have a spare cable, right?) and proceed to make your road side repair. Everything is going great until you have to trim the extra two feet from the end of the cable because you don't want it wrapping around your axle or crank. How do you do this?
I've broken a brake cable coming down the east side of Trail Ridge Road, no spare. But if I had a spare I wouldn't have had the tool to trim it to length. Fortunately I wasn't loaded (me or my bike) and I was able to make it down safely with frequent stops to cool my front rim.
I've also broken shift cables twice on my commute, first time no spare, so I used the stop screws on the derailure to select a reasonable rear cog and I three-speeded it home using my three chain rings. Second time I had a spare cable and I did a field repair. All went well until it came time trim the excess length. Guess what, nail clippers don't do squat and I almost committed hara-kiri with my swiss army knife, talk about a cultural faux pas!
I guess I could carry four spare cables all precut to length. I could even solder the strands, but who's that prepared? Let's say you carry universal cables for spares, you know the ones with a brake nub thingy on one end and a shifter nub thingy on the other. How do you cut the cable to make your field repairs? I really don't want to carry my Park cable cutting tool everywhere. The bicycle multi tools I've looked at don't have anything capable of cutting through one of these. Any ideas?