My opinion on this matter is that they are a waste of money. So much effort and money is spent on reducing unsprung mass and all this accomplishes is adding it right back. Most vibes are caused by outer tread deformation such as "cupping" and these are going to really do much for that...although the Dynabead says that it will. How the hell little balls in my tire prevent abnormal tread wear on a motorcycle is a mystery to me. In addition, I'm sure they do wonders to the TPMS sensors that are now being installed in some touring bikes. Lastly...if these things ACTUALLY (not anecdotes, but true lab testing) worked I'm sure that the company would've been gobbled up by now by a much larger company.