SKYWALKER CLIMB AND STEER TALL BIKE
SkyWalker is a radical two wheeler that allows the bicycle hacking adrenaline junkie to surf the skies while at the same time amusing or confusing the slack-jawed onlookers below. Sure, tallbikes are nothing new, and have been around since the 1800s, but SkyWalker takes things to new heights by allowing the rider to climb up and down the frame while the bike is in motion.
What this means for tallbike pilots is that they no longer have to cling to a telephone pole to mount the bike, and worry about finding another pole when it comes time to dismount. SkyWalker is designed so that the pilot can control the bike from the ground, and all the way up to the top while climbing the built in ladder. Since the handlebars double as ladder handrails, the pilot is under complete control of the tallbike during the entire ascent.
Why would a person want to build and ride a 12 foot two wheeler you ask? To win a Darwin award? Train for the circus? Overcome a fear of heights? Set a world record? Who can say, but for me it has always been the same reason - because it's fun, and it beats sitting on my butt watching the tube!
The photos presented here are somewhat low quality due to the fact that I built SkyWalker outdoors in early spring while the ground was still frozen, and did not actually intend to document it very much. Some of the photos were also taken at night, as I built the entire tallbike in one weekend just for a fun change.
SkyWalker is made of nothing more than a few standard bicycle components salved from the dump and a few lengths of thin walled electrical conduit from the hardware store. Even the curved tubes are nothing more than factory elbows. As for tools, I only used an angle grinder and a basic AC welder, nothing more. In other words, anyone with a pile of scrap bike parts and some tubing can do the same using any welder at all.
The SkyWalker idea was originally drawn on a coffee stained napkin, and then later transferred to a 3D concept as shown in Figure1. The 3D model was used to get a better idea if the steering and transmission would actually work, since the frame was somewhat complex and involved a bizarre linked steering system. Normally, I just grab whatever scrap metal I can find and go nuts with the welder when making crazy bikes like this, but for SkyWalker I decided to follow the 3D plan exactly so I knew the final product would actually work as planned.
The rear of the frame will be designed in a way similar to that of a standard bicycle - with stays that wrap around the wheel to hold it in place by the axle. Since I did not have a pipe bender, I simply hacked up some electrical conduit, and a few pre-bent elbows to make the part as shown in Figure 2. There are no measurements to give because I simply have no idea what they are. SkyWalker was built in a hurry using whatever scrap I had laying around, so I simply made things fit using the "try it and see" method. The large tube shown in Figure 2 is made from 1.5 inch conduit, and the stays are 1 inch conduit. There are two stays and two large tubes needed in order to form the rear triangle which will be shown later.
You do not require a pipe bender in order to make a nice rounded frame with lots of style. For this build, I just hacked up some pre-bent 1.5 inch conduit elbows and welded them together to create the curved frame sections.
The two rear pieces are joined together as shown in Figure 4 so they form a triangle. I decided to design SkyWalker with an impossible looking frame and remotely linked steering, so that it would confuse bystanders all the more. My design is certainly not the easiest way to build this kind of tallbike, but it does look cool. A huge A-frame would also work, but I wanted it to look as though there was no connection between the handlebars and the front wheel just to add to the confusion. As if seeing a madman on a 12 foot bike riding down the street wasn't enough!
The rear triangle is shown completed in Figure 5. The angle of the frame shown in the photo is at the approximate height when completed, allowing the rear of the frame to form a steep ladder. The frame could take on just about any shape imaginable, as long as the pilot's weight ends up centered between the two wheels. As for wheelbase, I think the distance between the front and rear axle should be at least half the height of the frame for stability.
The rear dropouts shown in Figure 6 were rough cut from some scrap 3/32 steel plate using a zip disc. Dropouts cut from an old steel BMX frame would also work fine. I was using a pair of heavy duty BMX wheels with 14mm axles, so I decided to make the dropouts equally as strong. The last thing you want at 12 feet is a frame failure.
The two head tubes will be joined together so that they are perfectly parallel to each other as shown here. A length of angle iron is being used as a guide to ensure that the head tubes are perfectly aligned and that the joint at the endThe front triangle will be another pair of 1.5 inch conduit tubes joined at the mid frame to form an inverted Y-shape for the frame. Again, I am building without any real plan or measurements, so I just strapped the rear of the frame to the fence and placed the front wheel and head tube where I thought it looked "right" and then cut the tube shown here.
Now, my wheelbase is half the frame height, and the seat will end up approximately in the center of the two wheels. As for head tube angle, it is about the same as the angle of the rear tube whatever that may be. Most of the welding was done outdoors in the freezing cold as the frame was too tall to fit in the garage, and almost impossible to get onto the workbench. s of the down tubes fit together with minimal gap. Don't worry about the width (track) of this trike; just take as little material away from each end of the down tubes as necessary, and the trike will be plenty wide enough for a safe ride.
This photo shows the second 1.5 inch conduit tube installed to complete the front triangle. Now, my tallbike looks like a giant inverted Y. Notice how there is no connection between the top of the frame and the head tube. Seeing this makes one wonder how the bike will be steered. The fence shown in the background is 7 feet tall by the way!
The frame needs to by trussed to make it more rigid, as the long 1.5 inch tubes have quite a bit of flex. The frame is certainly strong enough without the trussing, but the" floppy" feeling would be a bit disconcerting at high altitudes, and could lead to chain alignment problems. By creating many small triangles using some scrap 3/4 conduit, the frame is made to be extremely rigid and strong enough to support four riders all at the same time. Yes, I tried this.
Since the idea behind SkyWalker is to be able to climb while moving, a ladder of some sort will be needed. Using a few lengths of 3/4 electrical conduit, a crude ladder (Figure 10) is made. This ladder will be welded to the rear frame tube so that the pilot can get from the ground to the seat in approximately 10 steps. This ladder system worked out very well, and it was possible to get from the seat to the ground in under 5 seconds. On a conventional "pole hugger" tallbike, your only option is to find another pole for landing or face the consequences of gravity. For this reason, conventional tallbikes are usually made with seat heights of no more than 8 feet.
The two ladder halves are welded to the rear frame tube as shown in Figure 11 so that the brave pilot can go from the ground to the seat without needing a pole to lean against. The angle of the frame makes climbing very stable, and it is almost impossible to lift the front wheel, even if you lean way back while climbing. The filly trussed frame is also extremely rigid, and could easily take 500 pounds all the way to the top.
The seat post is welded directly to the frame on the curved section of tubing as shown in Figure 12. An adjustable seat could also be made by placing the seat post through the frame and welding a clamp to the tubing, but adjustability was not a huge concern here. It's not like I planned to run the Tour de France with this beast!
Once you are happy with the alignment between the front and rear of the frame, weld the entire joint right around the fishmouth cut. At this stage, the frame is not ready for any weight, so do not let the eager young pilot jump on the frame as it may bend the down tube where it joins with the bottom bracket. The frame needs a few more small tubes in order to form a triangle, the strongest of all structural shapes. By hacking up the leftover frame tubing, you will be able to make the two tubes needed to form a triangle between the front and rear of the frame. This photo shows the seat stay tubing cut from the rear of the two frames that were used to make the front of the trike. Sure, you could use any scrap tubing with a diameter of 3/4 inch, but recycling is the way to go.
The upper handlebar bearing is welded to a leftover length of bent conduit so that it adds to the artistic look of the frame. This tube (Figure 14) will then be welded to the open end of the long tube that runs from the rear wheel to the top of the frame.
SkyWalker needs a bottom bracket in order to allow the installation of the cranks, so the assembly shown in Figure 15 is made using another salvaged bottom bracket and some leftover 1 inch curved conduit tubing. This assembly will be welded to the vertical frame tubing at a position that allows pilots of average height to easily reach the pedals.
SkyWalker's handlebars are actually a large loop made from 1 inch conduit. This allows them to span the entire height of the frame, allowing the pilot to begin steering from the ground and climb up the entire ladder while maintaining total control of the bike. Well, total control may not be the best term to use, but you can certainly make it from the ground to the seat without any real problem. I often ascended the ladder while riding down a narrow sidewalk, so the ability to steer and climb was certainly acceptable. Figure 17 shows the four factory elbows and length of 1 inch electrical conduit used to make the handlebar loop. The handlebar loop needs to be wide enough so that it does not interfere with pedaling while steering.
To mount the top and bottom of the handlebar loop to the bearings, a steel crank set is hacked up for the ends of the arms that contain the square holes. As shown in Figure 18, this small part is welded to the center of the handlebar at the top and bottom where they will connect with the bottom bracket axles used as handlebar bearings.
The bottom bracket boom tube will be welded to the front of the trike frame as shown in here, directly ahead of the rear frame joint and at an angle roughly parallel to the ground. Since chain routing is also a consideration, it might be best to read ahead and understand how the boom angle will affect chain routing.
One thing that did not show up on my 3D model is the chain interference problem. To solve this minor chain rubbing annoyance, a small idler pulley was installed as shown in Figure 20 so that the chain would not rub on the rear frame tubing. This pulley also helps to keep the chain nice and tight so that a derailment will never be a problem. As I have learned from past mistakes, a loose chain on a tallbike is not a good thing.
To keep the clean flowing lines of the frame free from the chain line, I added a pair of kid's bike sprockets to the top of the frame as shown in Figure 21 so the chain would run inside the frame rather than dangling in front of the frame. These small sprockets are actually what are leftover after hacking of the crank arms on the crank sets.
The two front forks must turn together, taking into account Ackerman steering angles, so a pair of steering control arms are made from some 1 inch pieces of flatbar. The steering control arms are 2 inches long with a rounded end that will conform to the shape of the front forks, where they are to be welded. You will also need the appropriate sized bolts to pass though the ball joints and the control arms.
What good is a rolling piece of art without your personal signature? Because SkyWalker attracts loads of attention, I figured it would be a good idea to add my website address to the frame so other local (loco) bike builders could get a hold of me. The banner (Figure 24) is made of 1/16 inch sheet metal cut on a plasma table.
To make SkyWalker stand out against the bright daytime sky, I decided to paint it completely black. As you can see in Figure 25, the dark frame really stands out against a light colored background. At first glance, the complex design does not reveal any indication as to how it is actually possible to steer the beast. Many people think I have to learn to steer the bike.
SkyWalker turned out to be extremely easy to ride once you learned to trust the bike. With a few pushes, you could casually climb the ladder while the bike rolled ahead, keeping it under total control. Once at the top, you jump in the pilot's seat and start to pedal. Getting back down was simply the reverse procedure. If you visit the website shown on the banner (Figure 26), you can see a video of SkyWalker in action.
Because of the rigid frame, SkyWalker can carry as many riders that have room on the ladder. At one point, I had four people (including myself) hanging off the frame as I rode around. Once you beat your fear of heights, SkyWalker rides exactly like any bicycle, and it gives you a view of several blocks in all directions. I often took the tallbike out on the street and felt very safe as I could see so far ahead, and I was certainly visible in traffic to say the least. When I had to stop at an intersection, I just climbed down the ladder - a process that took about 5 seconds. Getting back to the top was as easy as giving the frame a push and then climbing back up the ladder.
I think SkyWalker really turned out well considering it was hacked together in a weekend with no real plan using basic tools and scrap bicycle parts. I am now working on a 30 foot tall bike using the same basic design as SkyWalker, and plan to break my 2005 Guinness Record again sometime. The new tallbike will be called "Bad Altitude", and will feature two pairs of cranks so the pilot can get the bike up to speed before ascending the 25 foot ladder.
Tallbikes are always crowd magnets, so be prepared for the spotlight wherever you ride. Newspaper and TV reporters will want your story, you will be chased down on the street for photo sessions, and traffic will part so you can pass. If you like to attract attention, then a tallbike will certainly put you in focus. I like it when onlookers try to figure out how SkyWalker actually steers or how I get on and off.
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