Steps to reproduce the behavior:
r You are too heavy to mount horse
https://en.wikipedia.org/wiki/Heavy_cavalry
0.D-4039-g02eaddfe85-dirty
[
"dda",
"no_npc_food",
"aftershock",
"crt_expansion",
"alt_map_key"
]
This probably means that the 20% of horses weight is a good maximum carrying capacity still..... but there needs to be horse variety.
Heavy Cavalry needs big strong horses.
This is working as intended, your average horse is not heavy calvary, and in fact I'd be sceptical of finding any heavy calvary capable horses. Feel free to provide any sources you find that say otherwise.
Huge pulling horses like Clydesdales aren't uncommon, they aren't warhorses but they should probably exist.
Someday of course we'll need the ability to give your horse some "horse alpha" mutagen...
Horse breeds are very different too in my mind. i dont think plate armor was a big thing in america so the horses were more suited for cowboys or so?
https://www.horsetalk.co.nz/2015/08/18/too-fat-ride-horse/ suggests smaller horses can carry higher percentage of their weight, also it depends on whether there is/the saddle structure.
Also, the bigger was your horse, the heavier the armor it needed to carry, since its surface is bigger.
According to wiki, the modern draught horses are even larger than it was necessary for medieval heavy cavalry needs. Seems like another 300 years of active horse selection all over the plaet were not in vain and most horses we meet today can be considered 'alpha horse', compared to medieval ones.
There are some 'light' horses, but they exist for racing purposes. So the probability to meet such horses is even lower.
Long story short: regular draft horse is enough to carry both armored knight and his armored girlfriend.
Wrote this up on Discord and not seeing too much here:
https://en.wikipedia.org/wiki/Heavy_cavalry#Renaissance_to_20th_century
https://en.wikipedia.org/wiki/Horses_in_warfare#Medium-weight dispute on heavy weights as actually being medium weights
https://en.wikipedia.org/wiki/Horses_in_the_Middle_Ages#Size_of_war_horses more on heavy cavalry horses actually being smaller than believed.
https://en.wikipedia.org/wiki/Destrier#Breeding_and_size charger-type (heavy cavalry warhorses) were smaller than believed
https://www.reddit.com/r/history/comments/685apv/do_any_ancient_war_horsedestrier_breeds_still/ more stuff suggesting size and current breeds.
http://www.humanesociety.org/sites/default/files/archive/assets/pdfs/hsp/soaiv_07_ch10.pdf a few years older, but gives details on the number of breeds in USA as well as some charts for New England and number of horses
https://www.thesprucepets.com/most-popular-horse-breeds-1886146 Assuming the cost of purchase, care, training, stabling and so on for horses, it can be safely assumed that popularity equals ownership for the most part.
With that in mind, from that list, there are a few breeds hardy enough and the right size (or even larger), such as the https://en.wikipedia.org/wiki/American_Quarter_Horse#Breed_characteristics, https://en.wikipedia.org/wiki/Thoroughbred#Breed_characteristics, https://en.wikipedia.org/wiki/Morgan_horse (smaller range but official breed of Vermont), with the draft horses being the higher end.
In terms of weight limits, everything I've read suggest horses should only be carrying 20-25% of their body weight. For simpler terms, I'd suggest 20% for non-draft horses, and 25% for draft horses, whenever someone decides to granularize mon_horse into actual New England breeds (with maybe one rare breed).
A very quick Google search indicates 240 pounds as a recommended maximum total load for a typical horse. Bear in mind that this figure was probably devised with the horse's well-being in mind. That might not always be a priority for your survivor, but it's still a consideration. Maybe overburdening a horse should be possible, but with pain, stamina loss (I don't actually know if NPCs have stamina) or damage dealt to the horse over time?
Also there is the possibility of horse variants/breeds as others have pointed out. If we can have multiple dog breeds I suppose it's not that different for horses.
i dont think plate armor was a big thing in america
https://en.wikipedia.org/wiki/Conquistador shows images of conquistadors wearing plate armor as well as other, lighter, varieties. Not sure how authoritative that is.
Most helpful comment
Huge pulling horses like Clydesdales aren't uncommon, they aren't warhorses but they should probably exist.
Someday of course we'll need the ability to give your horse some "horse alpha" mutagen...