That is wrong too. It doesn't matter how long or short the rod is. The piston will move exactly the same distance up and down based on the distance from pin center to crank center. That up and down movement is the stroke.

Bill, It's stuff like this taht almost ruined my hobby when I worked at hobby Shack as an engine fixer. I had to argue with these guys all the time. Finally gave up. I ended up agreeing with all the goodball ideas that came along.