There is a discussion in the Long Distance Forum on this. Go read it for some relevant information which I am not going to repeat here (I am about to set out on hopefully back-to-back centuries).

But in brief, we are talking about marathon runners; there was as far as I can see no extension to cycling as the OP said. And the closest that any riders in the 50+ forum come to similar are those who do regular LD -- and there are very few of them.

In addition, there is a balance needed needed between fluid and electrolyte intake (Gaorade blurs all this because of its sugar content and is not, in my opinion, a good sports drink because it plays havoc with insulin).

The danger with these articles is that people hold back on drinking when they should actually be keeping their intake up, and they end up dehydrated with as serious consequences as those portrayed by overdrinking.