I'm trying to portray their confusion and disbelief as it slowly peels back into a new world view that allows for previously impossible things. But I take about 86 pages to identify the problem (not the cause, that won't happen till awhile later). You are seeing the fall-out of the problem, which seems effective to me because it is the unseen approaching threat that is more terrifying than the one that has already arrived, but some of my feedback has been that things aren't moving fast enough or after two chapters they still don't know what's going on...
So I guess I succeeded in allowing them to feel the confusion of the characters, but I don't want to turn readers off either. I feel the progression is natural, honestly I don't feel like it should be changed, but what are your thoughts? On portraying ignorance and confusion?
I've learned this in a particular story of my own lately. It's not that that it's too long, it's that it needs to be more interesting. For that, you usually need to add details. There also the possibility that you need to be deeper in the head of the character. If the reader can move along with the MC trying tofigure things out, being fed little new discoveries of information, like breadcrumbs, they'll go along with you happily and not notice how long it is - hopefully.
So look at the 'slow' bit and make sure leaving clues and also ratcheting up the tension as you go. Every discovery should build a little more understanding and a little more suspense. If you're leaving your reader too much in the dark, and too confused, they have nothing to hope for, nothing to go along with. Another OSC quote: "Suspense comes from what you do know, not what you don't know." Let your reader know things, give them a mystery to solve. Get their brain working and they'll be happy.
Mel
However, if you suffer from too-many-words syndrome, that can have the same effect, of removing momentum. Cleaning up such prose restores pace and involvement.
Any takes for a quick three chapters? Four perhaps for measure, just looking to this one aspect?
By the way, if you have that wide a variety, it may not be a problem. I'd worry more if everyone were saying the same thing. But send it on and I will give you my take, for what it's worth. I may need a few days on it.
Unfortunately I can't just come out and say "hey, these saddles don't have stirrups" because stirrups don't exist and if they did and people knew about them then they'd be using them. But it makes it awkward because how else do you explain the difficulties of riding without stirrups?
The best I could think of was mentioning that their legs hang down loosely and they hold a saddlehorn. Not sure if it paints the correct picture, but I'm at a bit of a loss for what else I could do.
But the big problem with not having stirrups is that you don't have any leverage beyond the grip of your legs, which ain't all that much when clamped around an object the size of a horse's ribs. It'll hold you there, but it won't hold you PLUS an impact there. Get whacked, or even try to do a serious shoving, and over-side you go. A saddle with a high bow and cantle could keep you from being dumped fore and aft, but won't do a thing for side-to-side.
The other thing is, the harder you grip, the faster the horse wants to go (horses generally being trained to respond like that so they can be controlled with legs alone, and tending to move away from pressure) so as you're gripping with your legs trying not to get shoved to the ground, your horse is gonna become inclined to bolt out of there (barring training to the contrary).
Probably this is where we should unearth a SCAdian who actually does this sort of thing. 
What most people think of as a knight is from the Middle Ages. The Bronze Age was roughly from 3,000 to 1,000 BCE. Stirrups seem to have been invented sometime during the 4th and 8th centuries.
In a bronze age, a soldier might wear a breast plate and greeves (shin guards). What we would consider a ranking officer might also wear a helm. Most soldiers wearing armor would be in leather or even wood, and most swords would be short so that the metal could hold up in combat.
A horse carrying a bronze age soldier would carry less weight than one carrying a stereotypical knight. Calvary would train for speed and maneuverability, and I would expect them to avoid close combat. Bowmen and spearmen would be more useful than swordsmen.
I recently looked up bronze-age weaponry for my story. I wouldn't even come close to pretending to be knowledgeable, but it seems the famous leaf-bladed swords were determined to be the most durable way to shape bronze, usually only a foot and a half at most.
This creates a bit of a problem for my story, since my guys are swinging around greatswords and bastard swords, but I used the lazy, easy way out by saying the bronze was shaped around a core of cold-hammered iron. I can't even pretend to say whether or not that would actually work.