Originally Posted by
8bits
I'm not familiar with the rationale. I don't think anyone knows why.
This is just as arbitrary as the "bikes must be under 15lbs" rule. Years ago when people were making super light bikes, the UCI figured that to keep them from being too flimsy and therefore unsafe, they would require that they be 15lbs. So, if you are 230lbs or 130lbs, your bike cannot weigh less than 15lbs.