The Physics of McGarry’s 72 Foot Flip

Words Mike Berard
Date Oct 13, 2015

What does it take to nail a 72-foot (21.9 metres) backflip over a gaping chasm that threatens to swallow you? It takes precision, experience and an innate understanding of physics. Kiwi freerider Kelly McGarry showed up to Red Bull Rampage in 2013 with all these tools in spades.

In the video above, watch as McGarry’s electrifying feat is dissected through a scientific magnifying glass and spelled out in numbers:

  • He starts 91 feet (27.7 metres) above the canyon gap
  • He lands on the in-run going 31mph (48.2kph)…
  • …and must reach 40mph (64.3kph) before the takeoff
  • If he went one mph (1.6kph) slower McGarry would fall four feet (1.2 metres) short
  • If he went two miles (3.2km) faster, he’d land nine feet (2.7 metres) lon
  • He launches on a 38-degree angle
  • He travels at 30 feet (9.1 metres) per second
  • 50 feet (15.2 metres) above the canyon floor
  • 72 feet (21.9 metres) across the gap

And then watch what happens when you overshoot the landing, as McGarry did in 2014.

Kelly’s had some nasty crashes since then; will he throw something huge again this year?


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YeahyeahIllsignup  - Oct. 14, 2015, 8:15 a.m.

I have a hard time seeing how they measured and considered rider input in this.

It's easy to simplify the problem and consider McGazza as a simple projectile (that would have worked for calculating his trajectory in his latest stairset adventure). Those numbers about speed resulting in under or overshoot are pretty much crap since they don't take into account what the rider did (pop or swallow the lip).

But hey, mountain bikers love cheap physics so why not!


Wig  - Oct. 14, 2015, 9:07 a.m.

"must reach an optimal speed of 40mph"
At 39mph he "would land short of the target by 4 feet."

"He launches on a 38-degree angle"
"He travels at almost 30 feet per second [20.45 mph]"

Good thing Kelly was not listening to that guy.
HAHA, I know what he is saying though. Kelly compressed for the flip and launched at 38 degrees that basically made everything else in the vid irrelevant, but made the trajectory ok at that speed.

Pete Roggeman  - Oct. 14, 2015, 9:53 a.m.

You're right, of course. But the alternative to calculating it without all factors considered (including wind, aerodynamics, altitude, and humidity) would be to not go through the exercise at all. In which case you would have just watched a blank space for 2 and a half minutes, instead of that video. I found it interesting, even if it did treat Kelly's participation in the physics problem as, essentially, meat.


YeahyeahIllsignup  - Oct. 14, 2015, 10:06 a.m.

When the choice is between false information or a blank space, I tend to choose the blank 😉

Especially when the info is stated as facts with no disclaimer of the limitations.

Pete Roggeman  - Oct. 14, 2015, 3:25 p.m.

Oh, c'mon, man. Does anyone watch a Red Bull vid and expect a university-level physics treatment in this context?


YeahyeahIllsignup  - Oct. 15, 2015, 8:36 a.m.

You guys are often very quick to act defensive. You first reponded with a fallacy presenting a false choice (watching this of watching a blank space) and then you assume that I have unrealistic expectations when I simply had no expectations to begin with!

I'm not saying that I expect university level classes in a red bull vid.
They are the ones pretending to explain physics, and they proceed in doing it wrong!

I guess what I'm saying is that if it's worth doing something, it's worth doing it right.

Cam McRae  - Oct. 15, 2015, 10:27 a.m.

We are not! 😉


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