I'm writing a fantasy with a lot of story focused on the training of young warriors on horse-back, and the training of their mounts, now how much detail can the non-horse mad person handle in my story? Easy to carry on when I find it interesting.. I know that the details should be tied in to the story, not just be tacked on for the sake of it.. I'm concentrating on the MCs' experience of her training and how her character grows through the difficulties of the demanding training. I don't just want to write for those who are into horses, I want to interest a wide readership, so how much is too much?
I know just what you mean. I am not a horse enthusiast and reading Cormac Mccarthy's 'All The pretty Horses had me totally bemused at times but the writing was so good that it didn't detract from my enjoyment. The horsey details were matter of fact and part of the lives being portrayed. Sometimes the reader has to enter a different world and see if they enjoy it. If the writer is good, then often they will. From your brief plot notes, it sounds like you can ease the reader into the technical side of horsemanship. How much is too much? One man's meat is another man's poison. In a short story, I would think that you would want to ration the detail and leave the non horsey readers guessing so that you can concentrate on the MC. Why not post a sample and judge from the response? Best of luck.
I read quite a lot of military stuff even though I've never served and a lot of the details fly over my head pretty often, but I still like that they are there. They add to a certain feel, they add credence, and when the POV characters are soldiers/sailors, it makes sense they also pay attention to a lot detail I understand nothing of. But it doesn't bother me, and a lot of it probably has nothing to do with e.g. me understanding the situation is dangerous. So I wouldn't be too worried about putting too much horsey stuff there, unless you start to describe the shape of the cantle of a typical medieval saddle right in the middle of battle or something.