[verve_rat]

Maybe they don't need to be hidden that well. If one or slip past then you can track those to the warehouse and send a few people to jail.

After that people can add fake trackers (maybe an antenna lead under the seat). Now the thieves have extra uncertainty, raising the cost to steal. And working trackers will be mixed in with the fake ones, making each bike a gamble.

[ImaCake]

This strategy works well in biology. Have one brightly coloured poisonous frog and then there are three or four mimics who are not poisonous (poison requires lots of resources!). Sure, some frogs still get eaten, but the mere threat of poison reduces the risk.