If you’re like me, and you didn’t grow up in a particularly agricultural part of the world, you may think that tractor pulls are the height of simplicity. Just pull something as far as possible. And you’d be right. But achieving something simple can be really hard to do.

Perhaps the most surprising part of the motorsport is what makes it a competition. For something that can be described simply as a thing that gets pulled, the sled that the tractors tow is a devilishly complicated thing, as this video from the YouTube channel Smarter Every Day shows.

Host Destin talks to the operator of the sled, who actually sits in it as the tractors pull. The sled itself has several grousers that dig into the dirt to resist being dragged. To give the tractors a fighting chance, though, it starts on wheels and a weight moves forward as the tractor pulls.

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That has the effect of putting weight closer to the tow hitch, whose height is regulated, and makes the sled harder and harder to pull through the dirt as the wheels rise up into the air. Getting it as far as possible means carefully managing the torque of the engine and its weight distribution as it moves down the strip.

The racers interviewed in the video swear that there’s an ideal height that the front wheels should be off the ground to maintain optimal grip, and it’s their job to manage that with throttle, speed, and little weights that they can move around the tractor before the pull.

Tractors with big block engines, for instance, are less adjustable because the engine is so heavy and fixed. Speaking of engines, it surprised me to discover that, at least, some of the ones in this tractor pull were being run dry. They’re able to operate without oil because the seconds-long pull simply isn’t long (hopefully) to make them overheat.

Ultimately, though, the point of the competition is simply to see who can go the farthest. But despite this seeming like a simple endeavor, it’s actually a surprisingly nuanced and difficult thing to do well.