Well I come from a family of large people and I am the largest so far.
Last time I checked my weight (two days ago) I weighed 341 pounds
And I am six feet and about seven inches tall.
So am I too big to ride a horse
For the right sized horse, and if you are athletic enough, no. Depending on what type of riding you want to do many breeds are plenty large and strong enough..but you do need to be athletic and not just hang on. Andre the Giant was an avid rider.
Definitely depends a lot on the horse. The general rule of thumb is that horses can carry 20% of their body weight, but there are always exceptions. How your carry yourself (as mentioned above) has a lot to do with it as well. A bigger horse is a must. Did you have something specific in mind?
Depends on what school of thought you subscribe to.
There's the 20% rule where the rider and tack should not equal more than 20% of the horse's weight. I believe that would put you comfortably on a horse that was 1500 - 2000 lbs. This would be a draft, or draft cross.
There are other things to consider. If you are a good, balanced rider, if the horse has dense bone and good muscle, etc.
I'm also going to agree that you're not too big, but you will have a bit of difficulty finding a horse that is able to carry someone of your size. Like others have said, a good draft cross or even full draft would likely be a good place to look.
Whatever breed you find, the horse itself needs to have very good and sturdy conformation; big feet, big bones, good angles, a short back that is strong, a big and strong barrel, etc.
Just as an example, both these horses are draft crosses but this guy with his short strong back and thick, correct legs
Is much more suited to carry heavier weights than, say, this guy with his dropped front pasterns and light bone mass
I am not very athletic but I am starting to be more active.
I don't know much about horses or horseman ship I have never been riding,
So I don't mean what was said about the bars not going past the last true rib but
I would like a explanation of what that means. Thank you all for your information it
Has help me look in the right directions. Oh and what is the barrel of a horse.
If you are serious about this you need to start reading about the subject. You need to learn the physiology of the horse, tack (saddle and all the stuff one sticks on the horse), and beginner horsemanship. There are lots of books and info available. Most tack stores have a good choice of material for sale.
Then, if you are still interested, it would be a very wise decision to find an instructor who could give you lessons. There is so much more to riding than just getting on and going. Just getting on a horse can be work...unless you are young and spry. And I would make an attempt to get into a fitness program. Larger people can develop muscle tone and strength and that will help a lot.
Good luck to you.