Speedo cable with Columbia overdrive

[Kube]

The way that cable is looped beneath the car is exactly what Columbia CO. advised / illustrated.
I have shortened the cable to eliminate that loop simply for a better appearance.
Breaking in ten miles suggest there is something else binding. Perhaps the drive gear?

If you are unable to shorten that cable and remain confident that is the issue, you buy a kit (amazon, ebay, etc.) and make the cable and length you like. The kits are cheap and easy to use.
To shorten the housing, twist off one end (I usually do the lower end), cut the housing and twist the end back on.