Women are not excluded from the Tour de France due to any conspiracy by men. Cycling was a professional sport before lots of contemporary games were invented and before most of them became paid endeavours. Why? because no-one would race around France, over cobbled or unmade roads just for the challenge of it- and in 1903, who could afford to do such a thing, paying their own way?
Science and culture being what they were in the early 20th century, I'm sure few people believed women capable of cycling at speed for any distance when the Tour idea was devised. Nowadays there are a number of paid professional woman road racers, some of whom would definitely give some male professionals a run for their money in certain races which suited them. For example, I could imagine top female climbers beating heavy sprinter types in a hilly race like the Classique des Alpes. Problem is, no big rider would enter the CdA and at the present time, no female professional could generate the power to climb at a competitive speed with the men. The Tour de France requires such a high degree of all-round ability and such powers of recovery that, to date, no woman has seriously considered the prospect of riding; no team has even hinted at the possibility, even though these commercial enterprises usually would do anything for publicity........

So no-one in cycling thinks women should ride the Tour- and a parallel version exists for women to compete over parts of the same course. Some contributors to this forum think this is an inadequate response to some sexist plot. I would not disagree that cycling mirrors society in it's less than edifying attitudes to women's equality but the clear fact is that women would be uncompetitive. Cycling is one of dozens of sports which have responded to this situation by creating separate competitions for women. This is no more a reason for apology than it would be in the context of Track and Field, Rugby or Basketball. I see no theoretical reason why this state of affairs may not change in the future but no prospect of that happening any time soon. The 10% gap people are discussing here is indeed a chasm. That doesn't stop athletes like Jeannie Longo, Greta Waitz , Joanne Somarriba and Marion Jones being revered for their achievements. On the contrary, the present system allows people to win medals and fame in competition.
I have trained with a number of top female cyclists (Road and MTB). They are/were fine athletes, period- and represented their countries at world and olympic championships- but they were not in the Tour de France calibre, even the Tour Feminin......

In 1967, Beryl Burton became the only woman to that point holding an outright record in road time trialling, when she covered 277.25 miles in 12 hours. This British woman was a multiple world champion and is, to my mind, one of Britain's greatest ever sports figures. She earned the respect of male competitors and made female rivals wish she would race against men all the time LOL! She achieved enormous amounts in a deeply sexist era and without the training and nutritional advances of today.....oh, and she was an amateur, with parental responsibilities and a full-time, physically demanding job.....

Sure, women can beat men and maybe one day all sports will be arranged without the boundaries that presently exist....but I'm not holding my breath. Beryl Burton would never have entered the male Tour; she was so competitive, she wanted to win.