To ride fast and maneuver well you would need dexterity
I disagree. I personally am terrified of horses. Ive never ridden nor would I, with or without a saddle. Im pretty small, body wise, strong and dexterous.
Now, ive been face to face with farm horses, well, face to top of thier legs maybe, anyway, people ive seen ride and manuvour well, seem to be VERY strong.
It seems to take a COMMAND over the horse, physically, and im sure other ways too, that requires, not only strength, but a large body of muscle too.
Ill be riden a Springbok in game, so dex I feel should apply to that