It's 70mph
I always remember it as 70 just looked it up and it said 70 to 75mph so 80 is close enough, still fast as heck though.
How is that known?
How do you convince a cheetah to run as absolutely fast as it can? Are all cheetahs capable of the same speed (some people are faster than others...)?
A predator generally goes as fast as it needs to in order to catch its prey, but just because it doesn't catch up to something doesn't necessarily mean that it couldn't...
How accurate is the system for measuring the top speed of a cheetah? How many different specimens do you need to check to know you've measured the top speed of the fastest one?
I'm actually pretty interested in this subject, because it's so similar to verifying how fast a falcon can fly. For years top speeds of a peregrine were estimated in the 80-150mph range, but that was really just a bunch of guesswork. Now that more effort has been put into actual documented measurement it's been found that they can exceed 275mph, and can likely go faster than that. But the same questions come up... How fast can they really go, and how do you convince them to do it while you measure it?
I can tell you that from first-hand experience an animal traveling at upwards of 150mph is really impressive. When they dive it sounds like a giant blowtorch, or someone ripping a giant piece of paper. You can hear it a LONG ways away, and when you hear it without being able to visually locate the bird it'll make your hair stand on end. When a falcon comes down and hits a duck or pheasant it sounds like a baseball bat cracking into a watermelon, and you have to wonder how that li'l falcon can destroy a larger duck or pheasant like that and come out unscathed.
When I'm flying my birds I seldom have them anywhere near top speed when they're right near me, but it's still awful impressive to have them whip past you 2-3 feet away while they're doing 75mph or so!
My birds could pass as exotic I suppose, but I don't really consider them to be "pets". More like hunting partners...