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 2: Making
I tried to stop myself but I could not resist putting on the inevitable blood splash.
I added a rim from a drinks can just to finish it off.