How Effective were Spears Against Cavalry?

[Domen]

For example this excerpt (check the link above to read everything):

Marquis Wu asked: "In general are there methods for taking care of the chariots and cavalry?"
Wu Ch'i replied: "Now the horses must be properly settled, with appropriate grass and water and correct feeding so as to be neither hungry nor full. In the winter they should have warm stables, in the summer cool sheds. Their mane and hair should be kept trimmed and their hooves properly cared for. Blinders and ear protectors should be used so as to keep them from being startled and frightened. Practice their galloping and pursuit, exercise constraint over their advancing and halting. Men and horses must be attached to each other; only thereafter can they be employed. "
"The equipment for the chariots and cavalry - such as saddles, bridles, bits, and reins- must all be complete and durable. Normally, the horses do not receive their injuries near the end of the battle but invariably they are injured at the start. Similarly, they are not injured so much by hunger as by being overfed. When the sun is setting and the road long, the riders should frequently dismount for it is better to have the men weary than to overlabor the horses. You should always direct movements so as to keep some strength in reserve against the enemy suddenly turning on us. Anyone who is clear about this can traverse the realm without hindrance."

Another interesting fragment from these Chinese sources (see the link above to read all of them):

King Wu asked Tai Gong: "When chariots and infantry engage in battle, one chariot is equivalent to how many infantrymen? How many infantrymen are equivalent to one chariot? When cavalry and infantry engage in battle, one cavalryman is equivalent to how many infantrymen? How many infantrymen are equivalent to one cavalryman? When chariots and cavalry engage in battle, one chariot is equivalent to how many cavalrymen? How many cavalrymen are equivalent to one chariot?"
Tai Gong replied: "Chariots are the wings of the army, the means to penetrate solid formations, to press strong enemies and to cut off their flight. (...) after the masses of the army have been arrayed in opposition to the enemy, when fighting on easy terrain, the rule is that one chariot is equivalent to eighty infantrymen, and eighty infantrymen equal to one chariot. One cavalryman is equivalent to eight infantrymen; eight infantrymen is equivalent to one cavalryman. One chariot is equivalent to ten cavalrymen; ten cavalrymen is equivalent to one chariot.
The rule for fighting on difficult terrain is that one chariot is equivalent to forty infantrymen, and forty infantrymen are equivalent to one chariot. One cavalryman is equivalent to four infantrymen; four infantrymen are equivalent to one cavalrymen. One chariot is equivalent to six cavalrymen; six cavalrymen are equivalent to one chariot.
Now chariots and cavalry are the army’s strong weapons. Ten chariots can defeat one thousand men; one hundred chariots can defeat ten thousand men. Ten cavalrymen can drive off one hundred men, and one hundred cavalrymen can drive off one thousand men. These are the approximate numbers."