A number of years back I was riding in a paceline and getting beaten up -
rolling terrain and cruising at 25 mph+. Well one of the riders was a woman
and it turned out that she was a very successful triathelete at that time (came
3rd in the nationals). I thought to myself, "Shoot I am only a fit
recreational cyclist. There is no way I should be able to keep up with someone
that strong unless there is a major gender effect on performance.". I recalled
that as I had gotten stronger I saw fewer and fewer females riding in the
groups I rode in.

So being a trained biologist, I started poking around in the literature looking
for physiological explanations.

1) Women's muscles are just as strong as men. Shoot that is a no brainer.
Muscle tissue is very similar from mammal to mammal so a gender difference here
would be amazing. Of course, men tend to put on more muscle mass because of
androgens and that makes men much stronger for strength events. Means men have
an advantage in sprints and short hill climbs.

But cycling is mostly aerobic. Where is the male aerobic advantage?

2) Men tend to have larger hearts for their body size then women. This means
more blood flow and more blood to muscles which means more oxygen to muscles.
So here you get a male aerobic advantage.
3) Men tend to have more hemoglobin in their blood then women. Hemoglobin
transports oxygen so here is another male aerobic advantage.

Now I am a cruddy sprinter but I have a lot of aerobic power. However, my
hemoglobin levels are not high for a male but my heart is very large - it is
large enough to cause concern but that is because it is just plain big - not
diseased. Diseased hearts tend to get enlarged as a way to keep getting the
job done.

So a woman who had a lot of muscle, very large heart and high hemoglobin levels
might be able to compete with men but not at the top levels. She would crush
other women though. Thing is that the top men would still have more of all
three then the woman would have.

Personally, I figure that if a woman is the same age as I am and she can hang
onto my wheel, then she is probably in about the same condition as I am and
maybe a little better.

Of course, women can have babies something which men can't do. I would guess
that women's bodies have made a few adjustments for this ability and come to
think of it without this women having this ability, none of us would be here.

Also, cycling is really neat. A strong fit female rider can still do things
like ride centuries with aplomb that the average person feels borders on the
supernatural.

But compete in the Tour de France? Well maybe a really tremendous female
athelete like Babe Diedrickson could have done it and then just be an in the
pack rider. Why do that when the same woman could dominate competing against
other women? Seems to be no percentage in it.
3)