Some doping book I read was saying that back in the 60/70s on the tdf the front runner would be haggling as to how to split the prize money if they let one another win certain stages and overall win. I could easily see some of these big teams with wads of cash doing similar
And another thing
Apart from doping, what about the other methods of cheating?
Taking the train (Maurice Garin) would be a bit tricky with modern TV coverage, but there's still mechanical doping and buying and selling races.
It's well known that bribery was quite common in the past - what about now?