If you use something like this: http://www.vehicle-wiring-products.eu/product.php/54/twistwrap-sleeving it closes up on itself once you wrap it around the cables. I've used it in the past and it works quite well
All my control wiring goes through my handlebars and not a single wire is outside of the bars. This will cause a real headache if I ever have to replace the bars, but it sure looks clean. I put the McDouglator regulator under the battery tray too. My battery tray supports grow into the seat(s) and pannier mounts, This is an old pic, I now have struts that go the the foot-pegs...not the perfect place to mount them, should be on engine, but they work.The new podtronics regs will not fit inside an original Miller box, they are too big. I mount them under the battery tray with 2 countersunk head screws, plenty of air flow and no ugly modern devices visible.........Just my way of doing it. My 2 pet hates on old bikes..........Poor wiring and components that look hideous, modern crimp connectors especially, and control cables that are draped over the engine, mostly because people don't know how to route them correctly, why hide one of the prettiest engines in motorcycling history with ugly spiders webs of cables and wiring. Just waiting for the flack from all the experts now............