My Knog Blinder 4 bike lights (which I love) have a weak point in the silicon strap right near the metal tensioner. Both of them broke there, so I modelled up a frame to replace the silicon with some outdoor climbing 3mm static cord that's 70c a metre.

The friction against the holes in the 3D model is enough to hold the climbing static cord when it's under tension, which means it can be easily adjustable for different sized handlebars and seat posts.

This solution works on both front and rear Knog Blinders.