Agree with cheiro1. Possible for certain types of horse who are fit and healthy, with good conformation. But certainly not all - I don't agree with people who say bigger people shouldn't ride (as long as we're realistic) its all about using common sense and choosing the right horse for the rider
I'm fed up with this debate, a stocky well made pony can carry weight better than a lot of horses. I'll admit I'm well over 14st and I ride my full up connie, obviously plus his saddle, and he makes no bones whatsoever about carrying me, if he did he wouldn't bounce about all day and jog home every hack!
I would much rather see a larger rider on a small compact well put together cob, than a 16hh TB!! (ETA clearly within reason, I don't mean put an 18 stone rider on a 13hh cob!)
Depends on the horse. I ride a compact 13.3 welsh D and have done for 8 years (but I did get her when I was 11!!)
Weigh about 11stone 10 now, but was riding her at my heaviest of 12 stone 7 and she still didn't bat an eyelid. Physio can't find anything wrong with her and she certainly copes.
12hh 'cobs' I've ridden can/could carry 12st easily. (Basing on gypsy cob builds.). But really it's common sense on what's in front of you as to what it can or should carry!
As said above, there are different types of cob. It doesn't sound bad when its a 15 or even 14 hand cob, but 10 hands 10 stone? I'm sure it wouldn't collapse under the weight but I wouldn't send a pair like that off hunting... Then again I can lift a 25kg feed bag and carry it for about 15 metres before I dump it on the floor for a break!
A 10hh shettie will carry what a 14hh show pony cannot. No hard and fast rules.
I have a stocky 12hh dartmoor who will carry me all day (not far short of 12st) and enjoy it. Not that I ride him all that often, and that's also part of the decision. What's OK now and then, isn't OK day-in, day-out.
I tend to judge on conformation, and then make sure by examining the look they give you when you come at them with the saddle...
A good 10hh Shetland could easily carry 10 stone - inch for inch they are the strongest breed of equine in the world. My 8st friend once had a little go on our 34" Shetland - and got carted off across the beach at a good rate of knots.
Definitely more to do with bone and build of horse/pony than height.