Bike thieves are a pain in the bottom; I thought that I would get my own back.
Ladies and Gentlemen, I give you . . . the bike spike.
When locking your bicycle in a dodgy area simply remove your saddle and replace it with the bike spike.
Please read on . . .
Step 1: Materials and Tools
A piece of wood and a chisel.
I took a piece of my Eucalyptus firewood.