The BIG AIR Self-Jumping Bicycles
New-design (no, really!) bikes produce a totally new trick.
They jump from any flat surface at any time, no ramp.
AIR TIME, the patent bike.
AIR TIME arched.
This design demands too much of the front fork. So the lift mechanics
were moved to the rear wheel for all other prototypes.
HUGE AIR, a much improved design.
HUGE AIR arched.
A good design except it's too heavy.
ULTIMATE AIR, the best of twelve prototypes.
ULTIMATE AIR, other side.
ULTIMATE AIR high.
ULTIMATE AIR high, other side.
The rider would be standing on the pedals, not seated.
One type of stirrup.
Stirrups are recommended.
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FAQs:
Q: What makes the bikes jump?
A: Squeezing the lift lever engages the mechanism that produces the jump.
Q: Can you ride it like a regular bike?
A: All day long, just don't engage the lift. But what fun is that?
Q: Can just anybody jump using these bikes?
A: Practice is needed to do good, clean jumps.
Q: What if the rider isn't going fast enough to jump off of the ground.
A: Then it feels like you rode up and over a very big speed bump.
Q: How else are the bikes different and unique?
A: With a stronger spring than is normally used for jumps, the ride is
like floating on a cloud as you make it bob up and down.
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AIR TIME is the bike in our patent, US 6,209,899. To see the patent, go
to: http://www.google.com/advanced_patent_search and put the number 6209899 in
the number-search box. (Do NOT try to use the USPTO's ridiculous web site!)
All these bikes change kinetic energy (energy of mass and speed) into
potential energy (energy of mass and height). Like when a pole vaulter
converts his running speed into height to clear the bar. Or when you run and
grab a rope attached to a high tree branch. How high you will go depends on
how fast you were running.
AIR TIME uses the front wheel to lift the front end on long fork rails,
while also pulling the rear wheel down by means of a cable. This produces a
unique flat jump, unlike rotating up onto a ramp front-wheel-high and then
landing rear-wheel-first, like a normal ramp jump. But this version puts too
much strain on the fork.
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OPERATION OF THE JUMP BIKES:
These all jack-knife the bike frame to thrust the bike frame and rider up
from the road to power the jump. Like when a rider does a "bunny hop" on a
BMX bike. They throw their weight up and then pull the bike up with them.
With these bikes, the bike does the work. The rider should pedal during the
lifting action to both add more height to the jump and also start to un-jack-
knife the bike. That way the rider's weight will sling the bike forward as
the bike reaches the low position.
The lift spring is helpful to produce an easy, high, clean jump.
To initiate a jump with AIR TIME, the lift sprocket, which always turns
with the front wheel, is pushed over to a dog clutch and engages it. Next,
the lift shaft turns the lift crank. Then the frame is pushed up by the
pushrod on the lift crank. This thrusts the rider up and produces the jump.
A 10" lift of the bottom bracket occurs in about 50" of forward motion. This
geometry produces good jump action while maintaining good road traction, but
without creating undue braking reaction.
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The procedure for any jump is to get up to speed, shift weight in line
with the lift axis, draw the feet into the stirrups, squeeze the lift lever
and then let the bike launch the bike and rider up. Keep holding the lift
lever in. Land and let the lift mechanism push the bike forward as it drops to
the low position. This is like dropping onto the back slope of a high, wide
speed bump. Release the lift lever when the bike is at the bottom.
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HUGE AIR has a longer wheelbase, longer rear frame and a semi-enclosed
lift sprocket. The front fork is a 26" suspension fork. There is no front
lift action. Squeezing the lift lever moves the lift sprocket to the left to
engage the lift arm on the lift shaft. Then the lift shaft turns the lift
crank on the left side, which pushes on the seat post by means of the pushrod.
The rear derailleur allows various pedalling ratios to be selected as
usual, plus tensions the drive chain as the rear lift frame swings down.
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ULTIMATE AIR is a modified 24" DBX Vanquish full-suspension bike that was
made into the present jump bike prototype. The rear shifter was deactivated,
but any cog can be selected by manually moving the chain guide while stopped.
The front shifter was removed because the chain has to swing down during a
jump, but any of the three speeds can be selected manually while stopped.
The rear brake lever is used for the lift lever, so that brake was removed.
To get as much lift as possible, the stock rear geometry has been modified.
A 10" extension from the frame pivot extends the wheelbase while leaving the
ground clearance the same when riding low. The suspension fork is stock.
The lift cog on the left side of the rear wheel hub is 24T and is bolted to
where a brake disc would go. The chainring on the pivoting rear frame is 50T.
The circumference of a 24" wheel is 6.3 ft. With a 50:24 ratio, full
height is reached in 6.4 ft. Pushrod action is 10" if the crank radius is 5"
and this results in a 13" lift. A 4" radius creates an 11" lift. The bike
weighs 42 lbs.
When the lift lever is squeezed, the chainring slides to the left and
engages the lift shaft. The crank arm on the right side is connected to the
pushrod, which pushes on the top tube suspension spring mount to jacknkife
the bike and produce the jump.
A lift-assist spring.
This is a very helpful component.
The activation fork-lever.
The turnbuckle tightens the lift chain.
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All of these bikes use conventional bike parts. Only bicycle-manufacturing
technology is used. Twelve completely different prototypes were built and
tested, all using home machine shop equipment. Commercial versions would need
to be lighter, stronger, foolproof and repaired with standard bicycle tools.
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This same concept could be employed in motocross races for a new genre of
"steeplechase" racing on flat property using portable barricades. No moguls
need to be plowed with bulldozers.