Hi i'm a cyclist who was born female.
The fact is, that if we ignore all trans athletes, the (cis)women who excel at sport are those who are lucky enough to be born with a "more male" physiology:
less body fat, higher testosterone, bigger lung capacity etc.
Sport by its very nature is not equal.
We know that there are athletes born with androdgenous sexual make up (caster semenya for example). I can see how on a philosophical level, trans-women expand this concept to considering that they are "women" lucky enough to be born with an entirely male sexual make up.
The fact is that dividing sports to provide a "womens" category is an arbitrary division. What is not fair to the "normal"/ (cis) women on the "womens" side of this line is that the goal posts have been moved so spectacularly and so rapidly, and not to their advantage. What about their rights to be able to compete in a biologically appropriate competition?
In cycling I sometimes can choose to compete in a mixed field. Even though cycling is a "non-contact" sport it can be intimidating because a "touch of elbows" is very different when the other rider is considerably heavier than you.
I don't mind calling transwomen "she", or even "women", maybe I can even accept that they are looking for a forum in which they can participate and compete in sport, but we have to find a way to do this in a way that doesn't erode the right of (cis) women to compete against other biological women - and I don't know what that solution looks like.