The Tile

Could be a good idea for a bike, provided the world takes it up and it will fit in a seat tube. The “Tile” relies on others to have the app and have it switched on to locate a stolen item plus at the moment is only supported by apple 

Tile

bike tag will never be the same again.

I could see these being stuck to the back of cars that cut me off so I can trace the driver back to their house under the cover of darkness.

I like your way of thinking