Huh? They're not. The pro circuit visited my 'burg a couple of weeks ago, and I got to watch 6 pro races, men's and women's. I didn't see a single pro riding a 1 x system. I'm also watching every stage of the TdF: not a single 1 x bike there either.

I saw very few discs either, except at the low amateur-lever (Crash 5).