This is one of those semi useless pieces of info I have in my little teal box.
You measure around the cannon below the knee.
8" of bone: Horse can carry upper limit of 154 to 168lbs 9" of bone: Upper limit of 182-196 lbs 10-11" of bone: Upper limit of 210 lbs
BUT It is more to do with the over all build and condition of the animal not some measurement like this. I think that many horses that don't have as much bone carry well above what this is saying it can. Equus had an article about it not that long ago.
A horse that is smaller in bone and build but in condition to carry a heavier rider can do so easier then one that is thicker in bone and larger but not in shape to carry that load. So I put it in a useful group but not one that you use as a clear judge of what a horse can really handle.
Man does not have the only memory, The animals remember, The earth remembers, The stones remember, If you know how to listen, they will tell you many things. - Claude Kuwanijuma - Hopi Spiritual leader