I had just built up a new bike, and was taking it for a break in ride, to get it all fit. I had the allen wrenches in my pocket so I could make the adjustments quickly. After a few stops to get the saddle height right, I wanted to lower the quill stem just a tad. What did I do? well, I wasn't going to stop, I mean the bolt is right there. I loosened the binder bolt while riding, and promptly flew into the curb.