Where would the real disadvantage be...

[AqD]

Another important question related to this is... how many arrows could carry a horse archer? There must be a moment in which they must attack... and there will be a lot of Triarii ready to massacre.

A standard sassanid cataphtact carries a quiver with 30 arrows, but nomads like sarmatians have quivers that can hold up to more than 100, and each of mongolian horse archer usually carry 30-150 or 200 arrows, not including those in supply wagons. In addition, they always bring remounts to battle and carry different bows and arrows for different tasks; In reality they're far more terrible than what you can get in EB.

[Jaume]

A standard sassanid cataphtact carries a quiver with 30 arrows, but nomads like sarmatians have quivers that can hold up to more than 100, and each of mongolian horse archer usually carry 30-150 or 200 arrows, not including those in supply wagons. In addition, they always bring remounts to battle and carry different bows and arrows for different tasks; In reality they're far more terrible than what you can get in EB.

Thank you, it is very interesting. But how long all these arrows last? I mean, 150 arrows (for example), mean 20 minutes of shooting approximately?

[Korlon]

I would bet those nomads could've shot those arrows even faster. Years of usage of the bow probably could've gotten their rates faster than an arrow per five seconds.

[bovi]

I would bet those nomads could've shot those arrows even faster. Years of usage of the bow probably could've gotten their rates faster than an arrow per five seconds.

Yes, as can be seen here an experienced archer can shoot every 3 seconds if he doesn't need to aim very carefully.

Edit: Go to about 2:00.