Posted on Leave a comment

How High Can You Ollie on the Moon?

Skaters have been dreaming about skating with moon gravity for decades. And when we finally got a glimpse of what it might be like in the Tony Hawk games, that curiosity has only gotten stronger. But you can already ollie 6 feet high in those games. What would it really be like? How high could you ollie on the moon for real? Thanks to Jon Gomm for the question. This was going to be an Ask Rad Rat video, but this was way more work than I would have ever imagined. So let’s imagine that this is taking place in a location like the hanger in Tony Hawk 2, just on the moon. It’s enclosed, there’s no need for a space suit, and we’ll ignore air and wind resistance in general. How high could someone ollie?

One of the things that makes it complicated is that there are two parts to getting height out of an ollie. The actual liftoff, or the vertical leap part of it, and then the amount of air you get by pulling your feet up. Vertical leap would be like jumping up with straight legs to try to dunk a basketball, and sucking your feet up is like this: picture you’re floating in space. Your feet are touching a wall. You pull them in as far as you can go. How much space can you create without jumping at all? An ollie is both of those things together, and gravity is only going to affect the actual leap part.

Clearing hurdles, doing high jumps, or any of that stuff isn’t really compatible with figuring this out in skateboarding. The first time I ran the numbers, I found that basically any average skater should be able to beat the world record. So there’s a lot of other stuff going on.

Let’s start by figuring out the crunch space. That’s what I’m calling the gap you make by pulling your feet up.

Here’s how it works. Everything has a center of gravity. If you were to spin the whole thing, it would rotate around that center. Most of the time, it’s right around the middle of your body. When you crunch together in the air, your legs come up, and your shoulders, arms and chest all bend down to balance it out. Your center of gravity will always be in the same spot during jumps, but you can squeeze out a lot of extra space by getting that crunch in. Exactly how much space?

I found a couple references saying that a man’s center of gravity is typically around 57% of his height, a couple of inches below your belly button.

I don’t know much about either of the world record holders, but the average man’s height in the US is about 5’9.5”. That would mean that his center of gravity is 3.2 feet off the ground.

Here’s Jake Hayes, who is tied for the world record ollie. His center of gravity is probably right around here at this point in his ollie. Using the exact measurement of the bar, I was able to calculate that he is able to get his feet about 11 inches from his center of gravity.

That gives you a crunch space of about 27 inches.

Now here’s where it gets stupid. When we take the height of the ollie and subtract out that crunch space, we’re left with the actual vertical leap amount. And before I decided to do things this way, I looked into professional athlete vertical leap records. I was seeing numbers in the 40s in inches. Some NBA players are supposedly up around 50 inches. So if they jumped as high as they could with their legs straight, the bottom of their shoes would be 50 inches high.

An average dude, not even an athlete, should be able to get around 20 inches according to some research I found. How high did the world record holders jump? You want to take a guess?

The record is 45.5”. There’s a crunch space of 27”. The world record holders had a vertical leap of 18.5”.

When I got that number, I was so mad. I worked on this for like 4 hours and then got a number that’s clearly wrong. But it’s not. And I’ll prove it to you 2 ways.

First, with our old friend math. He never leads us astray. I found the footage of the Ollies. Jake Hayes and Xavier Alford both cleared the same height. I can’t show the footage, but I counted frames to get some exact numbers. Jake’s ollie took 20 frames, but he landed with his knees bent. Xavier’s took 19, but his knees were only bent a little. If they landed with straight legs, completely canceling out the crunch zone, it would have been 18 frames. 

18 frames in a 30 frames per second video is exactly .6 of a second. That’s .3 going up and .3 going down. How far did his center of gravity fall in .3 seconds, from the top of the jump?

You’re probably not going to like it. 

1.4 feet. 17 inches. Even lower than I thought. If either of these guys kept their legs straight, they only would have cleared 17 inches. And I’ll prove it to you again.

I found a picture of Jake clearing the bar, and I straightened out his legs as much as photoshop’s black magic would allow me to. Do you want to see it?

Boom. Yes his butt is in the front now and I hope he never sees this abomination, but look at the feet. Counting pixels and comparing to the height of the bar, it’s showing as being about 18 inches off the ground. This isn’t very accurate, but at least you can see what I mean now.

But how is this possible? I saw a pro athlete jump 64.5” inches onto a stack of weights. Look it up and watch it. He jumps up, feet together, and lands on top of it no problem. Why is skateboarding so much lower? Could we get that much higher?

No. The answer is, skateboarding is really hard. For two reasons.

First is the timing. If you watch the contest on ETN or youtube, you’ll see what I mean. Some of the guys were able to clear the bar but not do the trick perfectly, either losing control of the board or landing badly or things like that. There’s much more to an ollie than just the jump part.

But the second thing is the physics of popping the tail. I knew this had an effect, but not nearly as much as I would have thought. So think about this. Instead of jumping off of both feet equally, you’re starting a jump and then one foot goes up while the other one pops. Remember how hard it was to learn how to ollie that first day. It’s very different from a jump. You can’t focus on pushing off of your toes to get that extra couple inches. You have to do everything to get the board in the air and to keep it with you instead. And that technique doesn’t give you nearly as much air. And popping the tail saps a lot of your energy too.

Have you ever jumped on a trampoline? I don’t mean bouncing. Just stand there completely still and then try to jump. As you push off the trampoline, it gives in and absorbs your energy and you might barely clear a couple inches no matter how much you put into it. When you’re popping the tail, you’re pushing down on the ground through your board, and then the tail drops down a couple of inches at the last second. And then, of course, you’re pulling a few pounds of weight with you in the air too.

This just goes to show how completely ridiculous skateboarding is. Don’t forget how hard it was when you started, or the time your dad thought he’d try to step on your board and instantly slammed on his face. This stuff is crazy complicated and difficult. Someone ollieing over 40 inches is practically a miracle.

Now with that said and done, we can take all these same numbers, change the amount of gravity, and we’re good to go, right?

No, of course not! If you look up an article on how high you can jump on the moon, they’ll all say that the moon has a sixth of the gravity of the earth, and therefore, you’ll jump 6 times higher. But it’s a whole lot more complicated than that, now that I actually have to get into it.

The problem is, if you only change the gravity in the midair part, that doesn’t tell the whole story. The gravity is lower when you’re crouching down and starting to build speed too. You overcome gravity a lot quicker, and more of the force from your jump goes into speed. So not only do you fall slower, but you actually take off quicker. So you go more than 6 times higher.

I’ll spare you all of the specifics, because I read a whole paper on this with experimentation to prove that it would be true, but suffice it to say that I believed they were right, and the number they came to with a little bit of rounding was 10 times higher.

That’s a vertical leap of 170 inches plus the crunch space of 27-28 inches. If we put Jake or Xavier on the moon, we could expect that they would be able to clear 16 and a half feet. That’s like rolling up to my house and ollieing right up onto the roof easily. Ride along the freeway and kickflip over an overpass, clearing 70 feet along the way.

But what about your grandkids growing up on Mars? What are their skateparks going to have to look like, when the world record ollie is over 6 and a half feet? Well that’s just regular physics in Tony Hawk games. So maybe that will finally be possible.

Leave a Reply

Your email address will not be published.