I'll try my hand at the latter half for you. Basically, the first half says that cycling no longer receives the same attention in the French press. Only two major races receive wide coverage, the monthly mags are struggling, and the press prefers to sell copy by covering their (also struggling) football team.
If I read it right, and excuse my poor French here, the author says that the doping controls are a joke designed to appease the masses without having true effect. I understood the last sentences to be a critique of the people who the author feels have linked cycling with alchemy. He also references bona fide scientists, yourself, who post theories about the cyclists with the goal of serving themselves, not the sport.
For context, I translated this "dans le même temps un vrai chercheur, le physiologiste américain Andrew Coggan, met en pièce les théories de ces personnages dont le but n'est pas de servir le cyclisme mais de s'en servir"
as this: "at the same time a real researcher, the American physiologist Andrew Coggan, puts forth theories about these people but the goal is not to serve cycling, but to serve themselves."
Again, I only speak/read rudimentary French and apologize if I got it wrong. Especially as my translation is not very flattering. There are French members of this forum who will hopefully find their way here to be of better service.