MILAN, Italy — In the 1993 cult classic “Dazed and Confused,” the star quarterback for a Texas high school, Randall Floyd, is told to sign a pledge that he will voluntarily refrain from taking drugs and alcohol over the summer, or else he will not play the next season.

“I may play football next year,” Floyd says to his coach, as he crumples up the mimeographed sheet of paper. “But I will never sign this.”

Riders from the Tour de France now stand defiantly in front of the International Cycling Union, which has asked them to sign a similar pledge: Refrain from using performance-enhancing drugs or risk losing a year’s salary. If they don’t sign, they don’t ride in the Tour, which starts on Saturday. Only one team so far, a French one, has obliged.

Two years into a devastating drug probe that left the 2006 Tour without any marquee riders; that now threatens to strip the American winner Floyd Landis of his victory, and that has left the race once again bereft of its favorites in 2007, riders are still scratching their heads over the new reality, as if to say, “You mean, we can’t use any drugs at all?”

“Nobody understands anything anymore,” world champion Paolo Bettini, who has yet to sign the pledge, said in a recent interview with Gazzetta dello Sport. “It’s as though cycling no longer has any rules. The Tour turns away some riders, the Giro [d’Italia] gladly accepts them — Spain has certain rules, Germany has others, and Italy has others still. We don’t know who’s in charge. It’s total confusion.”

It should be pretty clear by now what counts as a banned substance on the Tour de France.

Landis appears to be on the losing end of a series of appeals to defend his 2006 title, relinquished after authorities found an illegal level of testosterone in his system during the decisive 17th stage. The Pennsylvanian first blamed it on the two shots of Jack Daniels he put away the night before. Now he says he has no idea why he exhibited that hormone level. That defense does not seem to be working.

Memo to Bettini: Steroids are out.

The greatest concern for Tour officials, of course, is r-EPO. For drug scandal novices, recombinant EPO is a synthesized version of erythropoietin, which the liver produces normally. The hormone increases the number of red blood cells and, therefore, the blood’s ability to carry oxygen.

Those levels can be increased by such natural measures as a high altitude workout, or even cigarette smoking. To arrive at illegal levels, though, it usually requires a blood transfusion.

The danger is that extremely high levels of those erythrocytes thicken the blood to such an extent that the left ventricle finds it hard to pump — a suspected cause in a number of fatal heart attacks in professional cyclists since the blood-doping technique was invented.

The probe into r-EPO use knocked out an entire field of elites in last year’s edition — Ivan Basso and Jan Ullrich, among others. Blood samples from both of these riders were found in the offices of a Spanish doctor who was arrested for adding r-EPO to cyclists’ blood. Since then, Ullrich has retired, preferring to ride into the sunset on his own accord. Faced with a reduced sentence for his admission of “attempted” doping, Basso has vowed to continue to compete but will miss the Tour, again.

So again, that leaves a field of mostly undecorated riders for this year’s Tour. The entire top 10 will return, with the notable exception Landis. His presence will be replaced by this year’s favorite, Alexandre Vinokourov.

The star from Kazakhstan missed last summer’s race after his team was forced to withdraw because more than half of its riders were implicated in a blood-doping sting. Vinokourov returns with a revamped Astana team that includes Andreas Kloden, a perennial contender who finished third last year.

Just who gets the final nod as team leader probably won’t be decided until the final days in the mountains.

Finishing just behind Kloden last year was another top 10 veteran, Carlos Sastre of Team CSC. With his teammate Basso out of the picture once again, look for Sastre to finish somewhere on the podium. Hot on his heels will be teammate Frank Schleck, who won the stage to the Alpe d’Huez last year — the pinnacle of achievement for a climber. His 27-year-old legs are five years younger than Sastre’s, and he could prove to be the dark horse candidate.

The other duo to watch are Oscar Pereiro and Alejandro Valverde, two young, aggressive Spanish riders from the Caisse d’Epargne team — 29 and 27 years old, respectively. Pereiro enters the race as the presumed defending champion, pending Landis’s appeal, and will be the team leader. But Valverde’s trajectory into the highest echelons of cycling has been meteoric (he placed 11th last year) and if he outperforms Pereiro going into the later mountain stages, he could well end up as one of the Tour’s youngest winners.

Cadel Evans, Denis Menchov, and Christophe Moreau fill out the rest of last year’s top performers, while American eyes will be trained on Levi Leipheimer, the lone true contender from the U.S. this year.

Leipheimer won this year’s Tour of California as the new leader of the Discovery Channel team, but is an outside favorite for a podium finish in Paris. Then again, so was Landis.

Incidentally, Landis won the Tour of California in 2006, with Leipheimer tight on his rear wheel. In last year’s Tour, Leipheimer kept pace with his American counterpart through the mountains until Landis’s incredible, rage-filled finish on Stage 17. The Montana native may be an outsider, but he’s not to be counted out.

So is Leipheimer the new Landis?

If so, let’s hope he swears off the Jack Daniels.

jmoretti@nysun.com