How the Flybar Works


A photo of the Flybar
Image courtesy SBI Enterprises, Inc./FLYBAR
When compared to toys like in-line skates, scooters and electric skateboards, the pogo stick seems old-fashioned. But thanks to a complete design overhaul that includes replacing the tried-and-true steel coil springs with elastic bands, the pogo stick has officially entered the 21st century. It even has a newer, hipper name -- the Flybar.

What else makes it different from a traditional pogo stick? How can people bounce so high with the Flybar, and is it safe? Why are extreme sports enthusiasts excited about it? We'll answer these questions and more by examining this new twist on a traditional toy.

At first glance, the Flybar looks completely different from a pogo stick. Its aluminum housing covers its internal workings and gives it a futuristic look. The difference translates to performance, too. Flybar doesn't simply bounce riders a few inches off of the ground -- it launches them to spectacular heights.

Given the Flybar's amazing height potential, you might think there's some revolutionary science at work. But the Flybar uses the same scientific principle as a traditional pogo stick: elasticity, or the ability of a material to return to its original shape after its shape changes. Technically, any solid can exhibit elastic behavior, but certain materials are much more elastic than others. Brittle objects, such as those made of plastic, are only slightly elastic. When they reach their elastic limit, they break. Their limited elasticity makes them brittle.

Springs and elastic strings, however, are highly elastic, which means their shape can be deformed quite a bit before they reach their elastic limit. Because they stretch, they can store energy that can be used to do work in the future. This type of stored energy is elastic potential energy. As elastic potential energy is released, it is converted into kinetic energy, or energy of motion. Pogo sticks take advantage of this energy conversion process. As a rider bounces on a pogo stick, his weight and the force from his legs are stored as potential energy in the elastic material, either a spring or an elastic string. When the elastic material recoils, all of the stored energy is transferred back to the rider, who uses the thrust to bounce higher.

Strings vs. Springs
Both traditional pogo sticks and Flybars are capable of storing large amounts of potential energy, but they don't do it in the same way. That's because a pogo stick uses a steel coil spring, while the Flybar uses elastic strings, essentially giant rubber bands called thrusters. Springs and elastic strings differ in one critical way: springs can be compressed as well as stretched, but elastic strings can only be stretched.

Graph showing the differences between springs and strings behavior

What are the implications of this difference for a pogo stick? When a rider bounces on a traditional pogo stick, his weight and force from his legs compresses a steel spring. As the spring compresses (shortens), it stores energy. When the rider pulls up, or stops applying force to the foot pegs, the spring recoils, providing thrust to help the rider bounce higher.

When a rider bounces on a Flybar, he also uses his weight and force from his legs to provide the energy necessary to bounce. Instead of compressing a spring, he stretches (lengthens) a bundle of thrusters. As the thrusters stretch, they create tension and store energy. When he pulls up, the thrusters return to their natural length, releasing the tension and propelling the rider into the air. The elastic strings in the Flybar operate like a trampoline, with each string capable of generating up to 100 pounds of thrust.

Next, we'll look at the Flybar inside and out.

History of the Pogo Stick
Although the original pogo stick came about in the late 1820s, a practical design of the toy did not arrive until 1919. George B. Hansburg, an Illinois toy designer, responded to a request from Gimbel Bros. Department Store to improve upon a wooden pogo stick it had imported from Germany. Hansburg replaced the wood with metal, enclosed the spring and applied for a patent. Then he began producing the toy himself in an Elmhurst, New York factory. He called his company SBI Enterprises and continued to manufacture pogo sticks until he sold SBI in 1967 to Irwin Arginsky.

Arginsky kept the SBI name and the same basic pogo stick design, but he relocated the factory to Ellenville, New York. SBI still manufactures traditional pogo sticks alongside the newest addition to the pogo family -- the Flybar 1200. The Flybar was not an in-house innovation. Bruce Middleton, an MIT-trained physicist and inventor, approached Arginsky in 2000 with an idea for an improved pogo stick design. Middleton proposed that they replace the steel spring with a patented system of rubber spring elements. Arginsky saw the potential immediately and began working with Middleton to develop the first prototype.

Soon after, eight-time World Cup Champion skateboarder and longtime pogo fan Andy Macdonald joined the project team. After four years of research and development, SBI Enterprises, with the help of Middleton and Macdonald, arrived at the Flybar 1200 design and began selling the product in September 2004

The Sum of Its Parts

The Flybar's bounce is fully adjustable. Riders can engage and disengage the 12 thrusters to control the amount of force generated in the Flybar bounce. The recommended ratio is one thruster per 20 pounds of weight, so a rider weighing 160 pounds should engage eight of the 12 thrusters. The disengaged thrusters just hang slack and don't contribute to the bounce.

Engaging and disengaging thrusters is easy and can be accomplished with the shell on or off. New owners are encouraged to remove the shell to work with thrusters, which requires a special tool that comes with the Flybar. Once the shell is off, the same tool can be used to engage a thruster. Simply use the tool as a hook and lift the thruster hanger up and over the cradle sill in the upper mount; then lower the hanger into the cradle and withdraw the tool.

To disengage a thruster, insert the Flybar tool into the hanger's slot, lift the hanger up and out of the cradle and withdraw the tool. The disengaged thruster remains in the unit.

Flybar thrusters close-up
Image courtesy SBI Enterprises, Inc./FLYBAR
The higher thrusters in this image are engaged, while the lower ones are disengaged.

As users gain more experience, they can make these adjustments without exposing the thrusters by using special slots in the Flybar's shell.

While the thrusters do the real work of the Flybar, there's much more to one of these machines than rubber bands. Let's take a look at the other parts, working outside to inside.

Labeled view of the outside of the Flybar
Image courtesy SBI Enterprises, Inc./FLYBAR

A fully-assembled Flybar comes standard with the following parts:

  • Tool and tool storage area - All assembly and adjustments can be accomplished with the proprietary Flybar tool. The tool should be stored with the machine so the rider can adjust the piston or thrusters as necessary.
  • Top cap - The cap slides into the outer shell and six upper bolts secure it.
  • Handlebars and grips - The handlebars and grips are similar to those on a traditional pogo stick. A rider uses the handlebars to control the orientation of the Flybar relative to his body.
  • Outer shell - The outer shell, made out of high-strength, reinforced aluminum, covers and protects the thrusters and keep debris out of the piston.
  • Piston adjustment access holes - These holes enable experienced users to adjust the piston without removing the shell.
  • Hanger access slots - These slots enable experienced users to engage and disengage the thrusters without removing the shell.
  • Lower bolts - Six lower bolts connect the shell to the base of the Flybar.
  • Foot pegs - The foot pegs on a Flybar are designed for the wear and tear of extra-high bouncing and trick jumping. They're extra wide and flat on the bottom, making tricks possible.
  • Piston - The piston works together with the thrusters to make the Flybar bounce. The piston and the upper mounts of the thrusters are locked together in a fixed system. The lower mounts of the thrusters are attached to the foot pedals, which are allowed to slide up and down over the piston. Now consider a rider making a single bounce. As the Flybar makes contact with the ground, the weight of the rider is directed through the foot pegs toward the ground. This drives the piston upward inside the shell, which stretches the thrusters up to 300 percent. When the thrusters recoil, the rider is launched into the air.
  • Tip - The heavy-duty rubber tip covers the end of the piston and provides traction so the Flybar doesn't skid out of control.

Inside view of the Flybar
Image courtesy SBI Enterprises, Inc./FLYBAR

To see the internal parts of the Flybar, the outer shell must be removed. This reveals the following components:

  • Piston adjustment holes - Nine piston adjustment holes can be used to change the length of the piston and the height of the bounce.
  • Friction clamp and locking pin - The friction clamp and locking pin are part of the upper mount and are used to fix the piston into place.
  • Bearings -The sliding plastic bearings support the piston.
  • Upper mount -The upper mount receives the upper hanger of the thruster.
  • Upper hanger - When the upper hanger is situated in the upper mount, the thruster is engaged. When the upper hanger is removed from the upper mount, the thruster is disengaged.
  • Thruster - Each thruster is essentially a giant rubber band that can be stretched to three times its normal length.
  • Anchor - The anchor forms the bottom of the thruster and locks the thruster into the lower mount.
  • Lower mount -The lower mount receives the anchor of the thruster.

Next, we'll learn how to use the Flybar and about the two models available.

Using the Flybar

Fundamentally, using the Flybar is no different than using a traditional pogo stick. A rider simply grabs the handlebar and jumps on, placing his feet on the foot pegs. If he's standing correctly, his knees will be bent, his weight will be centered over the piston and the Flybar will be perpendicular to the ground. Then it's a matter of bouncing.

Riding the Flybar
Image courtesy SBI Enterprises, Inc./FLYBAR
Pro skateboarder Andy Macdonald on the Flybar.

Four factors affect the Flybar bounce: rider weight, leg strength, the number of thrusters engaged and the piston setting. The first of these four factors, of course, can't be changed, but by applying more force with the legs or engaging more thrusters, a rider can make the Flybar bounce higher.

The piston setting is also crucial to optimal bouncing. Piston length can be set to nine positions, from seven inches to 18 inches. The longer the piston is set, the higher the bounce. Most people can achieve a peak bounce height that is twice the piston length. For the average person, that means a bounce height of two to three feet. Some trained athletes, such as pro skateboarder Andy Macdonald, can bounce more than five feet off the ground. The record so far is nearly eight feet. With such height potential, the Flybar is turning traditional pogoing into an extreme sport with tricks and maneuvers. You can see a video of people doing Flybar tricks here.

Flybar Safety
Safety isn't as much of an issue with traditional pogo sticks because they don't bounce as high and are easier to control. Flybars, however, require more attention to safety. Helmets should be worn at all times. Before a jumping session, riders should check for hazards and make sure that the surface is solid, flat, dry and free from debris. A wide field of action is ideal for Flybar jumping, so riders should look for outdoor areas that give plenty of room to maneuver. Other hazards to avoid include:

A flybar trick
Image courtesy SBI Enterprises, Inc./FLYBAR
Pro skater Andy Macdonald on the Flybar.

  • Traffic
  • Pedestrians
  • Slippery ground
  • Overhead obstacles
  • Steep inclines
  • Soft or weak surfaces
  • Holes or uneven ground

Remember that while the Flybar bounce may be three to five feet off the ground, the rider's head can be 10 to 12 feet in the air. When the Flybar tip hits the ground, it can generate 1,000 pounds of pressure. That's why it's so important to check for wide, flat, solid areas free from low-hanging trees or wires.

Flybar Models
The Flybar 1200 was the first Flybar model marketed to the public. SBI Enterprises released it in September 2004 and designed it for experienced riders weighing up to 250 pounds. The name of the 1200 comes from its ability to generate up to 1200 pounds of thrust.

In the spring of 2006, SBI released the Flybar 800 for riders between 80 and 180 pounds. It can generate 800 pounds of thrust and launch riders up to four feet in the air. Less extreme than the 1200, the 800 is designed for teens and smaller, lighter adults. Children will soon have the Flybar 400.

Model
Weight
Thrust
Height Potential
Cost
Flybar 1200
21 pounds
1,200 pounds
five feet
$350
Flybar 800
12 pounds
800 pounds
four feet
$250
Flybar 400
TBD
400 pounds
TBD
$150

With all of these models on the market, the Flybar is likely to capture the imagination of users across generations. Best of all, it carries on the spirit and tradition of the original pogo stick, which relied on a simple, elegant design to provide hours of entertainment. The traditional pogo stick had limitations because of its coil spring. The Flybar, with its elastomeric spring system, does away with those limitations without relying on pneumatic or artificial propulsion systems. It's a pogo stick for the 21st century.

For lots more information on the Flybar and related topics, check out the links on the next page.

Other New Pogo Sticks

The Pogomatic
Image courtesy UC Berkeley Human Engineering Laboratory
The Pogomatic

Image courtesy Robotics Institute at Carnegie Mellon University
The BOWGO
Over the years, inventors all over the world have taken on the challenge of building a better bouncing toy. The Pogomatic is a power-assisted pogo stick designed by Tim McGee and Justin Raade of the Berkeley Robotics and Human Engineering Laboratory. It uses a pneumatic cylinder as the actuator for the pogo stick and is able to maintain a constant bounce height of several inches without requiring any energy input from the rider.

Another notable example of a design using elastic instead of springs is the BOWGO, a patented design that uses a fiber-reinforced composite spring that bends like a bow to store elastic energy. The BOWGO is a product of the Toy Robots Initiative at Carnegie Mellon University's Robotics Institute. The bow spring was first developed as a resilient leg that could be placed on hopping and running robots. Compared to the steel coil spring of a traditional pogo stick, the bow spring stores two to five times as much energy per unit mass and enables the BOWGO to bounce as high as two feet off the ground. The BOWGO isn't commercially available at this time, but may be soon.

Related HowStuffWorks Articles

More Great Links

Sources

  • The American Pogo Stick Company
    http://www.pogostickusa.com
  • The BOWGO Project Web Site
    http://www.cs.cmu.edu/~bowgo/
  • Flybar
    http://www.flybar.com
  • Hoffman, Mala. "Jump to it," Chronogram, April 2005.
    http://www.chronogram.com/issue/2005/04/artofbusiness/
  • "Monster pogo stick that could clear Yao Ming," Popular Science, 2004.
    http://www.popsci.com/popsci/bown/2004/recreation/article/0,22221,768215,00.html
  • SBI Enterprises
    http://www.pogosticks.com
  • "The Flybar - think of a pogo stick on steroids." Gizmag.
    http://www.gizmag.com/go/3570/1/
  • UC Berkeley Robotics and Human Engineering Laboratory
    http://bleex.me.berkeley.edu/pogomatic.htm