Even for cycling, there are about 8 subs that I'm on, and one out of the bunch is strictly focused on serious fitness & performance discussions, whereas the rest are sort of free-for-alls loosely based on the subreddit's sub-genre.
If there are no subs within the subs, might just gotta suck it up and scroll past the memes. Or start a discussion and find like-minded folks to branch off.