When I was a teenager I had to take a check to the bank for my mother. She told me to hurry as the bank was closed but the bank manager was waiting at the door for me. I got to the bank leaned my bike against the wall, looked at my watch to see the time, walked to the door and gave the manager the check. I went back to get on my bike and it was gone never to be seen again. Total time off the bike ? THIRTY SECONDS! Someone nearby must have seen me leave the bike unlocked and done a snatch and grab. A cable lock no matter how flimsy would probably have prevented that theft.

Cheers