#Person1#: So, to start with, I want to talk about a very successful invention, the bicycle. Why? Do you know what the main advantages of bikes are?
#Person2#: They don't cost much?
#Person1#: Yes, and they're not complicated.
#Person2#: They're easy to use. Yeah?
#Person1#: Not easy when you're going uphill. Let's say simple.
#Person2#: OK. Yeah. They're cheap to run. They don't often breakdown. They're safe.
#Person1#: Well, they're not too dangerous, so a successful invention for all those reasons. And with modern bikes, we have a good example of using the latest materials for a design that's over 100 years old.
#Person1# and #Person2# talk about the main advantages of a successful invention, the bicycle.
a successful invention