While moving my Harley around the garage an interesting thing happened. I grabbed the handlebar to lift the bike and heard a loud metallic snap. My handlebar immediately fell and nearly hit the tank. The lower clamp had broken.
I'm not sure why it broke. That should be a very strong component of the motorcycle. Seeing all control and handling is done through the handlebars this is a part that should never break. What I know is this: It was the stock Harley lower clamp. I had replaced the stock rubber bushings that hold it to the triple tree with polyurethane. Now I am thinking the new bushings may have caused the break. They won't "give" when pulled on like the stock rubber bushings. I think because they won't flex it puts strain on the clamp. The rubber bushings would absorb some of the movement when pulling on the bars. This would lessen the strain on the clamp.
That's just my speculation. I know that force will cause breakage at the weakest point. When you "upgrade" to polyurethane bushings the normal force point applied through the handlebars changes. That force will now be applied more on the lower clamp than absorbed by the stock rubber bushings. This is just my speculation. I'm just glad it didn't break while riding.