Rider to Mount ratio?

[Erik Vale]

While I'm away from my books and google fu is failing me, a simple question, How many riders can fit on a mount 1 or 2 size catagories larger?

Also, as a afterthought, If someone [say a wizard] teleports away with his mount, what happens to all the other riders [assuming the wizard can't normally take them]? I'm assuming they all share a stupid look before crashing to the ground in a rather ceremonial manner at the moment.

[Hamste]

I have heard about people talking about 4 halflings riding a centaur but I am not sure if there is any RAW rules to back this up

[bekeleven]

I normally ruled it that a mount could, out of combat, comfortably fit weight equal to his light load and space equal to himself. So huge mount could carry 16 medium/smalls. But I don't think it's RAW so much as how I interpreted things.