It is a megastructure.

An enormous dam, nine kilometres long

with four kilometres of sluice gates that can be closed

to hold back extreme high tides and stop the Netherlands flooding.

It took a decade to build and it is a rallying cry

of human planning, survival and achievement.

And it is not what I'm here to talk about.

There days ago, a forecast came in.

A storm is going to hit,

winds will gust up 120 km/h on this barrier.

And so a different rallying cry went up.

Three words: "We kriehen sturm".

A storm is coming.

Because today is NK Tegenwindfietsen,

The Dutch headwind cycling championships.

Several hundred Dutch people looked at this weather and said,

"We're going to have a bike race in that".

- The course is eight and a half brutal kilometres.

It's a serious event, with permissions and everything.

We have a limit of 300 participants.

All the bikes are the same. No gears, and just an ordinary brake.

And it's a typical dutch bike.

- Have you done it?

- Yes, two times.

- How difficult is it?

- Very. I do triathlon in my spare time and it's just as hard.

- At high speed, up to 90% of the drag on a cyclist is from air resistance.

And I naively assumed,

because it's been 15 years since I've studied high school physics,

that it'd be an equal action-reaction thing.

Double the wind speed, double the drag.

But that's only true when there's no turbulence.

In a situation like this,

the drag increases with the square of wind speed.

Double the wind speed, quadruple the drag force.

The difference between cycling in a 15 km/h headwind

and a 120 km/h gust is 64 times the added drag.

- Why are you doing this?

- I don't know. [laughs]

I really don't know.

- Do you regularly do bike races and things like this?

- No, just bike for fun.

- How do you think it's going to be?

- Hard! Very hard!

- Succes! - Dank je wel!

- And sure, it's a good, weird human interest story, right?

People are doing a deliberately difficult thing

and hurting themselves just enough that it's interesting.

But this is a good place for it.

Because not only are humans literally pushing against the storm

and saying, "we can beat you",

they are on a physical monument to doing just that.

There's a big rock in the middle of the barrier,

with an inscription that translates as

"Here the tide is ruled by the wind, the moon and us".