Cut an old tube into the shape of the tape you used. Start by taping one end of the tube to the bars with Scotch brand electrical tape(other brands move and lose traction eventually. Wrap the tube around the bar until it is thick enough,
then hold the end in place with some tape just well enough to hold it still when you put the light on. This method
allows you to make the shim the thickness you need for your light and bars. This allows more crushing of the shim for better traction, tape does not spring back the way rubber tubes do.