A friend of a friend is a gay, black and female cyclist, and I saw her riding Brighton Big Dog XC race a few years ago. All boxes ticked! Non-white riders do seem rare, I have a couple in my wider riding circle but that’s close to 100 people. At least one gay rider in that group, there could be more but we’re Brighton so it’s not exactly a big deal. And some women.
I had a conversation about this with a British Indian friend some years back when I coaxed him on an XC ride and he said that sport and outdoor pursuits were never encouraged when he was growing up, and that doing well academically being considered far more important.