I don't use many cavalry tbh. I try to have twice as many infantry as archers though. In my current Army of 119, I've got 65 infantry, 35 archers, 19 cavalry. I don't use horse archers because I'm a true Nord and that's a silly way to fight.
I play full realism, and as long as I don't go down, I can usually beat an army in the 160ish range fairly handily, except the Khurzaits. They hold me to equal numbers pretty well, so I've been taking larger archer forces against them.
Side note: Against cavalry heavy armies, just use your smaller cavalry force to distract their cavalry while you infantry ball their limited foot soldiers. Then form a circle of infantry with a square of archers inside. Or vice versa, a circle of archers and square of infantry inside. When they charge the circle, they lose momentum and smash into a ball of infantry ready to grind them down.