Locks that work

Saw a very suspect dude looking over the bikes outside my work today, not sure if he was just taking ages to roll a smoke or if he was eyeing up bits and pieces on the bikes.

Was thinking now that my setup is sorted about gluing in ball bearings.

What size ball bearings work best and what glue should I use to make sure they stay in whilst still being able to use solvent to get them out?

Size according to the Allen key needed, plus trial; and use wax. Remove with heat and gravity.