To plough through the metre-thick mud we get after it rains, of course! And it rains all the time. And to cross over all the dykes. And to stunt-jump over all the ditches. Yeah....
That enough cliches for you?
We're just a bicycle-loving country, figures some of them are mountainbikes, I guess. Though the way you put it, I agree that it might be just a teensy bit silly to have mountainbikes in the flattest country of the world