I'm thinking about it, but I don't know how well it will work. They get their location and talk to the internet by Bluetoothing to a nearby Apple device, so only good in a populated area I think.
Sticking them inside metal tubes is going to limit the range. Inside a saddle might be a good place.
Anyone planning to use airtags as a bike tracker? Can imagine they would be pretty good if they can be hidden inside one of the tubes