Just like to point out that your tests use pikemen, which have special bonuses against charging enemies and against horsemen in particular. If pikes work like they did in RTW then the charge bonus of an attacking rider is reflected back onto himself as his horse gets impaled on the spears. Therefore, a charging unit of knights is likely to suffer more casualties in the initial charge than if they just trotted within sword's reach and started hacking. I've lost 10-15 knights out of 40 just from the intial charge. You might have to switch to spearmen or swordsmen for better results.