Originally Posted by FBinNY

You did it wrong. You probably rode around the block a few times so you wouldn't have a long walk after the crank came loose. That was the mistake. You have to drive the bike to a fairly remote area with good cycling. Then you ride away from the car headed into an area with little traffic and no amenities (a lack of cell phone coverage also helps). Doing this at high noon on a broiling humid day also helps. The key is that the crank will not come loose un til you're assured of a long, miserable trek back.