Treebeard's Stumper Answer
It's fun watching the kids skateboard at school during their free time. I'm impressed how they can jump their boards high into the air over an obstacle on a flat sidewalk with no ramp. That basic maneuver is called an ollie. It's the basis for many more difficult tricks. For example, Shane likes to ollie into the air and spin his board along it's long horizontal axis at the same time. It looks like magic! The riders are not attached to their boards with straps (like skis), and they do not place a foot under their board to lift it. How is a skateboard ollie possible?
Shane doing an ollie over Whitney. Note there is no ramp.
How can he lift the board from above?
A skateboard ollie is really an illusion, but it's an effective illusion when done right. It looks like the skateboarder is lifting his board into the air from above. Actually the rider is kicking the board up into the air by stomping down on the angled tail of the board and jumping up at the same time. As the board bounces up into the air, the rider meets it with his front foot and brings it level. It appears that the rider's feet are attached to the board the whole time, but really the rider and the board are following their own separate paths. It's just physics!
Look close at the above photo. The leading edge of Shane's front foot appears to be on his board holding it level, but his rear foot is not quite in contact with his board. He's really jumping in the air independently.
Graybear sent this analysis:
I am also amazed at the gravity-defying acts that skateboaders can do. I guess we all enjoy the 'magic' of phenomena we don't fully understand, and I certainly don't understand how they do it. Of course, that won't stop me from taking a stab at it. My guess is that at the beginning of the jump Shane pushes down on the tail of the skateboard. This causes the front and center of the board to move upward, accelerating the center-of-gravity upward. This explains how the skateboard can stay in contact with Shane's feet, but I am still amazed when I see the board do a barrel roll (how does the board get accelerated that way?) in mid-air and the skater manages to land his feet on the board and the board on the ground in one piece. One of these days I'm going to videotape some skateboarders and watch the tape in slow-motion to unravel the secrets...
I can't process video, but I took several stills with my digital camera that show the process:
Kick the board up into the
air with your rear foot.
Bring the board level with
your front foot.
Get ready to land.
I was an early skateboarder (and surfer) in Santa Monica in the late 50s - early 60s. As I recall, my junior high school (Lincoln) was one of the first schools to prohibit skateboards on campus! We made those boards from a scrap of lumber and old metal skates that we cut apart. Those horrible skates had a bad habit of locking up when you hit a sidewalk crack. That sure taught the meaning of inertia in a way I'll never forget! The best trick for us was not to fall, so I really love watching the kids ride today who do so much more. I'm impressed that the ollie was invented by Alan "Ollie" Gelfand in the late 1970s. Or was it discovered? We didn't know about it back then, and it probably wasn't possible on our old flat boards.
I can't skateboard now. (I can't work a hula hoop either!) My timing and balance are all off, though I know just what to do. My mind knows the right moves, but my body lags just enough to throw me off. *Sigh* I guess that's age.
BMX and mountain bikers can "bunny hop" their bikes into the air on flat ground. Is that something different?
You'll find hundreds of links and many photos of skateboard tricks if you do a web search on "skateboard" and/or "ollie". Here are a few links to get started:
- The San Francisco Exploratorium has a large site on Skateboard Science, including a step-by-step photo analysis of an ollie and a movie. Ollie physics is also discussed in the New Scientist Last Word archive.
- There's tips and instruction for doing ollies and other tricks here and here. Enternet has a page of short videos including an MPEG of Jeremy Klein doing a huge ollie over a dumpster. Really! Of course there's a Skateboarding FAQ.
- The Discovery Channel Online has an interesting history of skateboarding. They say it started in 1958, which fits my memory.
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