The fact that Christian Prudhomme hasn’t gone over the edge and turned in to an axe-wielding psycho is remarkable.

Every year since he took over, the general director of the Tour de France’s beloved race has had its reputation hammered by leading riders getting caught cheating. In doing so, they have risked destroying one of the highest profile sporting brands on the planet.

In 2006 it was Floyd Landis, the winner of the tour, who was caught. The following year it was tour leader Michael Rasmussen, Aleksandre Vinokourov and the whole Cofidis team who were kicked out.

Sadly, this year we have Saunier Duval rider Riccardo Ricco, who had already won two stages of this year’s tour, being arrested and taken for questioning just before the beginning of the 12th stage. Two other riders - Spaniards Manuel Beltran and Moises Duenas Nevado - have already been ejected from the race for the same offence.

Again, it is EPO at the centre of the scandal, but with the sinister possibility of an even more effective drug that produces the same result – known generically as CERA. The logical conclusion is that if the drug is more efficient it can be used in lesser quantities, less frequently or both, making detection that much more difficult.

It’s difficult to predict what effect this will have, certainly the fans are still turning out in force and TV ratings are still excellent. Sponsors, on the other hand, are becoming a little gun-shy, but there are good signs.

Columbia sportswear apparently only signed as major sponsor for Team High Road because of the stringent internal anti-doping policy that the team has instigated. Maybe this will become the norm and is the answer to all of the problems.

Penalising the riders does not seem to be a deterrent, but the threat of financial oblivion might make the teams take the problem seriously. Instead of turning a blind eye to what is going on – and in some cases actively supporting it – the teams will have a real incentive to take action. Besides, they are the only ones in constant contact with the riders, so who better to control the problem?

Even when they are eliminated, those caught doping still leave a mark on the race. Who knows whether last year's tour would have ended up with the same result had Cadel Evans not “hit the wall” trying to chase down Rasmussen on stage 14 in the mountains. That day he lost 41 seconds on Alberto Contador. Evans finished the tour only 23 seconds behind.

Drug scandals aside, it has been a fascinating 2008 tour. The racing has been hard and fast with the requisite amount of thrills, spills and heroics for good measure. It’s promising to be a very interesting conclusion. Let’s hope it will be drug-free.