I can top that
There used to be an Emu farm on one of our longer routes. These very large birds were in some kind of corral. One day several years ago, I am riding by this farm by myself and I see what looks like an Emu outside the fence. I think to myself, "nah, that cannot be. They are in the pen."
Wrong!
This one had escaped somehow. Now, I know nothing about Emus or how they think. But, this one decided I was prey or something. I rode by it, and it decided to chase me. Man, those suckers can run. I am moving as fast as I crank, but this bird was gaining on me. I later looked at my computer and discovered I had hit 30 mph on the flat. Now, my normal top speed on a level surface is around 25 mph. Adrenalin is an amazing thing.
Just as I thought I was going to be bird food, the Emu farmer pulled up in a truck and lassoed this thing with loop on the end of a stick. Damn, I was happy to see him. He yelled "I'm sorry" and took big bird back home. I slowed down to let my heart get back to normal and then finished the ride.
The Emu farm is long gone, but I still shudder a little when I ride by it. I have never seen another animal - dog, deer, whatever - move as fast that thing did.