[mrWiz]

I think it would be hard to hide an airtag effectively on a metal-framed bike. Putting it in the frame would interfere with wireless communication and any other location would be easily discovered.

[benhurmarcel]

That's correct [1], but there are plenty of accessories to hide one pretty well still.

[1] https://www.youtube.com/watch?v=aLtWN1Mp2Qc