Parthian/Sassanid heavy cavalry use bamboo lances?

[ValentinianVictrix]

If the couched lance technique had been in use for many centuries by many different peoples how do you account for the superiority shown by the heavy cavalry of the Normans and other Westerners against Byzantium from the 1060s and against the Middle Eastern Muslim peoples from the First Crusade onwards? Please do not say armour, because Western armour at this time, though heavy, was not as diverse or effective as the armour used by their Byzantine and Muslim foes.

The Byzantine princess and historian Anna Comnena stated: "For a Frank on horseback is invincible, and would even make a hole in the walls of Babylon". Franks were obviously doing something that contemporary Byzantine cavalry were not.

Was it not the case that Byzantine cavalry were dual-armed and relied on mainly bow fire, whilst western cavalry lacked bows and relied on their initial charge breaking the enemy?