Slightly late reply here - if normal electrical tape keeps coming off (it will, it's not waterproof) & you really want to protect the wires, try using some self-vulcanizing rubber tape (in the US it might be called self-fusing tape?). Stuff is magical - been using it for decades for all sorts of things (at the moment I've got a layer under the indicator control pod on my Trident to fix the slight rotation around the bar that Triumph said couldn't be fixed).
Waterproof, very stretchy/flexible, insulating and doesn't stick to anything other than itself, so no messy residue if you need to remove it.
