You've just reminded me - I used to have friends who were keen cyclists, and I remember them pointing out to me that 'proper' bicycle saddles are binary and immutable because guess what? men and women have different physiques and therefore difference saddles are designed for each.
Anybody who has read Flann O'Brien's Third Policeman will be aware of the dangers of atomic interchange if a man uses a women's saddle, or vice versa:
“The gross and net result of it is that people who spend most of their natural lives riding iron bicycles over the rocky roadsteads of this parish get their personalities mixed up with the personalities of their bicycle as a result of the interchanging of the atoms of each of them, and you would be surprised at the number of people in these parts who nearly are half people and half bicycles.
“The postman?” I said.
“Seventy-one percent,” he said quietly.
“Great Scot!”
“A round of thirty-eight miles on the bicycle every single day for forty years, hail, rain or snowballs. There is very little hope of ever getting his number down below fifty again.”
But even after 38 miles every day for 40 years on a women's saddle, he still wouldn't be eligible to compete in races against women, right?