I think I’ve found the best place to hide a tracker on my Brompton: in its front carrier block!
It does require a Pebblebee Tag, as AirTag and Chipolo One are too big to fit. Just make sure to leave a space on top for the locking mechanism to fit.
Edit: I was told that AirTags fit as well, so I guess Motorola Moto Tag might fit too, as I believe they are roughly the size of AirTags.
@sanji @brompton: And what the picture does not show: There is usually a locking mechanism in that hole which will hide the tag probably quite well.
@axeleroy: Can you charge the Pebble Tag without disassembling the front block’s locking mechanism? How long does one charge last?