Using Magic Items

[by_the_sword]

What about riding a horse or some other land-based mount? In the LL Basic book it mentions that you can't cast a spell while on a flying mount, but if you can ride with your hands free, like horse archers, or knights used to, why then wouldn't Magic-Users be able to do the same? I realize that knights and horse-archers were trained to do that, but why wouldn't a wizard prepare bis apprentice in a similar manner?

Is there a ruling from the books on this?