I needed a quick and dirty way to hold my flashlight (Olight i3E EOS) to the handlebar of my bike since the front light died on me. So voilà… with the help of a rubber band i had a temporary light. 

I used some gasket tape on the bottom to fit it even better around the handlebar.  

Disclaimer:
Be aware of your local laws and regulations! This solution might not count as proper lighting for your vehicle wherever you live..