SKYSTYLE JOUST READY 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 belowIf you are going to be known as the neighborhood crazy bike inventor, then you will certainly need a tall bike in your fleet! A tall bike gives you the sensation that you are hang gliding without a hang glider! You get to face your fear of heights, confuse your onlookers, and peer into the neighbor's second storey window all at the same time!
I have been a fan of tall bikes ever since I figured out how to hack bicycles, and have even had some tall bike fame by getting my photo in the 2005 gold edition of the Guinness Book of World Records. Yep, that dude on page 134 slinging the Canadian flag would be me - cool bike, eh? Anyhow, you have not earned your bicycle hacking stripes until you have ridden a tall bike, so let's get building.
This tall bike is called the SkyStyle because it is based on a freestyle BMX bike, and would be perfect for jousting competitions and many other foolish tall bike tricks. The overall height is high enough that you have a good time defying gravity, yet not so high that you can't mount the bike without a ladder. Because we will keep the wheelbase the same as the original BMX bike, you can play fair at jousting competitions, pull wheelies if you dare, and many of the "flatland" stunts you might try on an earthbound BMX.
For starters, you will need to dig in the back of your tool shed for that 1980s BMX that your mom bought you after you watched Eliot fly through the air with E.T. in the basket. Actually, any BMX bike with 20-inch wheels will do the trick, just like the one shown in Figure 1 before getting the axe.
You need two decent 20-inch wheels, a sturdy frame, front forks, and all the crankset hardware in order to make the tall bike. Figure 2 shows all the parts disassembled, cleaned, and ready for severe modification.
The overall height of your final tall bike will depend on the length of the head tube plus the diameter of the front wheel. Since this tall bike is designed so that you can step up from the ground using foot pegs, you will want to keep the total height from the handlebars to the ground at reaching distance. The total height of my tall bike from the ground to the handlebars is approximately 7 feet, so the head tube was made to a length of about 5 and a half feet (7 feet minus the height of the front wheel to the top of the fork hardware).
You will need to find a tube with about the same inside diameter of the original head tube so that the bearing cups will fit inside as shown in Figure 4. A piece of electrical conduit or fence tubing may be just the thing you need.
Once you have chosen an overall tall bike height and cut the tube to make the head tube, you will have to cut and extend the fork stem to match the new head tube. Start by cutting the fork stem in the middle of its length as shown in Figure 5. A tube cutter does a nice job here if you have one.
To calculate the correct fork stem extension length, install the baring hardware as shown in Figure 6, and then lay the cups along the extended head tube so you can measure the missing section of fork stem. This will help ensure that all the fork hardware fits correctly once you have extended the fork stem to match the new head tube.
To extend the fork stem, find some tubing that is fairly close to the diameter of the fork stem, cut it to the required length, and then weld the parts together. Figure 7 shows the extension tubing I have found to make my fork stem longer. This tubing was cut from an old barbell, which had the exact diameter of the fork stem tubing.
Make the fork stem extension welds as strong as you can, ensuring that there are no crack or holes. Remember, if these welds let go, you will learn the meaning of free fall as you make an instant flight towards the pavement! Figure 7 shows the completed weld on one end of the extending fork stem. Also, ensure that the bearing cups fit over the weld, and only grind as much material as necessary if there is a little too much weld buildup around the joint.
When you are done extending the head tube and fork stem, the two parts should fit back together just like they did on the original bicycle they were taken from. Figure 8 shows the completed fork set and head tube with all bearing hardware installed. The forks should turn freely and without friction once everything is installed.
Now that your extended head tube is completed, you need to hack away the original head tube from the BMX frame so you can replace it with the new one. As shown in Figure 9, make the cuts as close to the head tube as possible to keep the frame tubing as long as possible. You don't want to shorten the wheelbase any more than necessary, or you will be doing wheelies all the time! You can also slice the head tube in half lengthwise and weld it directly to the new head tube if you want.
The new extended head tube will be installed onto the BMX frame as shown in Figure 10, just like the original head tube once was. The one thing to keep in mind is head tube angle versus handlebar-to-seat distance. As you add more head tube angle, the distance between the seat post and handlebars decreases, so you will have to find an angle that gives you the best of both worlds. Draw an imaginary line straight up from the original seat post tube and then try to install you new head tube so that the distance between this imaginary line and the top of the head tube is no less than half of what it is at the bottom of the frame.
Dude, does that make sense to you? If not, let me explain it another way. If the distance between the original seat post and head tube of the BMX frame was 28 inches, then the distance from the top of the new head tube to the new seat post should not be less than 14 inches.
The seat tube must now be extended upwards vertically as high as the top of the new head tube as shown in Figure 11. Any length of 1 inch or 1.25 inch tubing will do. I used a bit of electrical conduit that was lying around the shop. The new seat tube should extend upwards from the frame at an almost vertical angle, keeping in mind that the more it leans back, the easier it will be to wheelie your tall bike. Maybe you want this instability for a jousting tournament? For the best stability, try to plant your butt ahead of the front wheel, not over top of it.
Cut and fit the new top tube by making the appropriate fishmouth cuts at each end of the tubing. Tack weld the ends of the tubin in place for a test fit. All welding is done when the frame is all tacked together.
Your tall bike is almost ready, but the frame will need some reinforcement if it is to withstand the crashes that will surely be coming in the near future. With only the head tube and seat tube extending the frame, the ride would be seriously wobbly, and the frame would easily warp if you were to mow into a curb or smack head on into "Sir Bleedsalot's" tall bike during the jousting finals.
By adding a simple truss between the open frame, you create a triangle, which will make the frame many times more rigid and stable. This tube can be any appropriate length of 1 inch or even 3/4 tubing and it is installed as shown in Figure 13.
To step up to the cranks during a mounting procedure, you will need a lower set of foot pegs unless you have abnormally long legs. You can purchase some nice foot pegs at the bike store and weld a bolt to the frame to hold them, or build the poor man's foot pegs as shown in Figure 14 from some scrap tubing and a few washers. The washers are a safety precaution that will save your hide from impalement during one of those wonderful moments when you are lying on the road and your tall bike is falling over on you. Oh yes, you will understand this one day, I promise!
The lower foot pegs are installed on the lower part of the extended seat tube as shown in Figure 16. This position makes it "easy" to step up to the pedals as you launch the tall bike from a standing start. If you plan on being a total maniac of the sky, then add more pairs of foot pegs all over the bike, so you can astound your buddies on the ground with your fancy footwork.
You will need to hack a bottom bracket from another frame in order to install the cranks onto your tall bike. The best way to do this is to cut it from the donor frame so an inch or so of the original tubing is still there as shown in Figure 17. This way, you can simply weld the tubing stubs directly to the new frame.
If you get lucky, the distance between your crank set and rear wheel sprocket will be just perfect so that you can join together your new chain and have it nice and tight. You can move the rear wheel slightly in the dropouts to pick up some of the tension, but there is a chance that your chain might be way too slack once it is made.
A chain tensioner is needed when you add one more link and your chain is too long or if you remove a link and the chain is too damn short. Any 1/2 inch V-belt idler pulley can be used to pick up the chain slack by simply welding it in the correct place somewhere on the frame. An example pulley is shown here.
Figure 20 shows how the idler pulley can be used to pick up any chain slack that cannot be taken up by simply moving the rear wheel in the dropouts. Join your chain until you have as many links as necessary, and then hold the pulley somewhere on the frame so you can mark the best place to weld the bolt that holds it there. A tall bike chain should be fairly tight, as a derailment will mean a dismount - an ugly dismount if the chain happens to get tangled in the rear wheel!
Figure 21 shows the finished SkyStyle tall bike, complete with a sloppy black battle-ready paintjob. Hey, why worry about paint quality on a bike that is certain to end up in a tangled mess at least a dozen times during a jousting competition? The thick clothing helps me avoid road rash as well as the harsh sub zero climate of Northern Ontario!
Mounting the SkyStyle tall bike is a process that is easily learned. As shown in Figure 22, step one involves gripping the handle bar with one hand as you kick off from the ground to get the bike rolling while one foot is on the lower foot peg. It may seem odd to steer a bike by reaching 7 feet into the air, but if a monkey can learn to ride a unicycle, then you certainly have no excuse!
As shown in Figure 23, step two of the launch procedure is a little more precarious. At this point, you must not only steer the tall bike from one side as it leans, but also climb from the lower foot peg up to the pedal on the opposite side of the bike. Hopefully, you had the pedals in the correct position before you started. Oh, did I forget to mention that? Oops. Now you know.
If you are actually standing on one of the pedals with both hands on the handlebars as shown in Figure 24, then you are past the hardest part of the launch procedure and home free. If your launch has not gone well according to plan, then you are lying on your back on one side of the street, with your tall bike on the other side of the street as the neighbors point you out to their kids through their picture window. "Now, Billy, this is why I won't let you play with that Brad kid. He's a bad example." You know the routine by now!
Well, we hope you have fun with your SkyStyle tall bike. Watch out for low hanging power lines, and remember to put your hands out in front of you on the way down during battle! Figure 25 shows the SkyStyle pilot out for a leisurely ride, free of ankle biting dog attacks, and highly visible in traffic.
Oh, and yes the tall bike does have brakes; they are built into the rear wheel in the form of a coaster brake which engages when you pedal in reverse. Have fun, play safe (but not too safe) and respect the laws of gravity!
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