While driving my Op Cruiser home from work at about 30mph, my back wheel locked up. Thankfully I didn't eat it, and no-one was driving behind me. I'm also very lucky that my wife answered the phone and came to rescue me so I didn't have to carry my bike all the way home. I first thought that the chain had jammed, or the clutch had gone out, but no, one of the bearings in the back wheel exploded or melted (see pic). I had only been going 30mph off and on for about 10 minutes. Has this happened to anyone else? I replaced the back wheel with a '60's Bendix brake cruiser wheel knowing that it would take more abuse, but I'm still a little scared of using my bike for transportation. Are there any more measures I should take to insure that this NEVER happens again?