Quote Originally Posted by Burns
So now, how does one counter a heavy cavalry charge?
One endeavours not to be on the receiving end

Seriously though, pikes in deep formation, longbowmen with stakes, your own heavy cavalry, horse archers/crossbowmen/javelins, AP infantry charging in after the knight have spent their momentum, all of those can counter knights efficiently enough. And of course, a castle wall provides adequate protection too ;)