They are anti cav weapons
They are bad anti-cav weapons unless you're facing retarded cav, stay hidden around a wall or the cav underestimate your length. Even then, it's only when some cavalry underestimate the length and I can stab the horse's face from the side that the pike is a better anti-cav weapon than the bamboo, bill and long awlpike. I killed tons more cav when I bamboo, bill and long awlpike. Pike doesn't pack the punch, every cav can see it from miles away (and won't get close to them because they're not retarded) and it's painfully slow. However, in group combat the pike rocks, totally. It's length can terrorize the opponent's infantry mob. A timed thrust to a charging enemy can one-hit if you hit the face and abuse the speed bonus, and even if you don't, you'll still create doubt within there ranks, having a long weapon dealing quite massive damage (when used right)
Cav underestimate bamboo and the long awlpike. and they're not as easy to spot from far away (especially the long awlpike). They're also strong enough and fast enough to take down most horses when you've reared them, unlike the pikes. If you one-hit the horse with say the long awlpike, you'll definitely one-hit the rider by stabbing his head on the ground.
It's the opposite of what you said. Long Awlpike and Bamboo Spear are anti-cav, long spears and pikes only repel cav within a 3m radius of the piker himself, but their massive length makes them great for infantry support. I've used all of those weapons (english bill, bamboo spear, long awlpike and pike) dedicated for a long, long time.
