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Free of charge, they’re issuing microchips you place inside your bike. In the event your bike is stolen, you report it and the chip’s ID is tagged as stolen.
Kindly traffic wardens walking the streets carry a gizmo that beeps when in range of a bike containing a chip tagged as stolen.
So while it’s not quite a tracking device, it’s a sort of alert device, giving you some hope of getting your bike back.