I appreciate projects that are simple, can actually be made using novel technologies and which really work well for the task at hand. Among them are those that try and see if pedal power can be applied in any fashion to solving practical problems, however outrageous they maybe. And there should be solid reasons behind choosing pedal power.
Now PlasmaCAM Cutting Systems is a Colorado based company that markets an automated CNC cutter. This is a robotic cutting tool which is touted as being more versatile and more accurate than a plasma torch, achieving metal cutting accuracies as high as plus or minus five thousandths of an inch.
Now the most important part.
Knowing that he would have a live car weight of 500 pounds, Bailey's math led him to use a 450 long, 250 pound stainless steel cable of 1/2 inch diameter. A hydraulic tensioner was used to test the cable at 22,000 pounds before each use. A portable air-compressor powered rock drill was used to dig deep into the rock, as far as 5 feet! Then, multiple expanding anchors were used to tie the cable into the bedrock. Finally, tripod supports were built out of 2-inch by 3/16-inch-thick square tubing to take as much as 5000 pounds of down force at the peak cable tension during testing. The cable pulleys would be located on these supports at what would be a perfect resting height for the bike on the cliff.
For the operating conditions of 500 pounds live weight at a cable tension of 14,000 pounds, Jason calculated that the cable would sag 4 feet in the middle of the canyon. See source.
How he got the cable between the two ends of the cliffs is the highlight of the story. Below, he describes this strenuous feat in his own words :
"People often ask how I got the cable across the canyon. It was no small feat, as the entire cable weighs about 250 pounds. I started by rolling the entire spool down to the bottom of the canyon. Next I lowered a 150-foot climbing rope down from the top of the cliff. With the bottom of the rope clamped to the end of the cable, I pulled the rope back up the cliff from the top while the cable was unwound. The last bit of cable was difficult to pull up because it became so heavy. I was barely able to get the end of it wrapped around a tree and clamped.
I dragged the other end of the cable back up the slope while the cable was untangled. I wrapped it around a tree at the top and clamped it as well. I used a hand-cable-winch and many pairs of locking pliers to gradually reel in more of the cable to the trees I was using at both sides of the canyon. I attached the climbing rope to the middle of the cable so I could work it up through the trees as it raised. This proved difficult, because the cable got caught in so many tree branches. One tree was especially large and stood right in the final path of where the cable needed to go. With the ends of the cable merely wrapped around trees, I actually rode the skybike out to the big tree and sawed the top of it off, about 100 feet off the ground."
ADDITIONAL READING AND RESOURCES :
Design Case Study : Pedal Powered Hotdog Launcher Design
Design Case Study : Cherry Bomb Mountain Bike
Design Case Study : Innovation Of The Brompton Bicycle
Design Case Study : iBike Power Meter
Inventor Jason Bailey builds the Skybike