My handlebars on my Raleigh Sports started to rotate while I was out riding. When I got home I tightened the stem clamp but they still rotated so under pressure so I tightened some more and stripped the stem bolt. For the time being, I added three washers above the nut so that nut would be on thread. It still rotates under normal force of riding. I have a feeling the problem is with the handlebar serrations or lack their of, but the handlebars are otherwise in great shape, with good chrome. I am purchasing another Raleigh bolt (with the stem, from eBay). I would rather not have to purchase another handlebar too.