The article will discuss a method of creating a tandem of two faulty of bicycles. The whole structure is assembled using sticks and electrical tape, according to the author. It is not difficult to guess, the project is quite simple and not financially expensive if there are unnecessary bicycles.
The bike is planned to be assembled like the one that can be seen in the photo. According to the author, it should turn out to be twice as powerful, as well as more dangerous and more interesting.
Materials and tools for tandem assembly:
1. In total, two bicycles will be needed, from one the front part is assembled and from one the rear.
2. Hacksaw for metal (will facilitate the work of the grinder).
3. Wrench (adjustable);
4. Tool for squeezing chain links.
5. A coil of electrical tape.
6. A screwdriver.
7. The hammer.
It is important to note that both bicycles must be male, that is, they must have a high tube, the upper tube of the frame. Also, the bicycle must have a front gear shifter, while on the two smallest sprockets the number of links must be the same in order to get the same gear ratio.
Tandem assembly process:
Step one. Disassemble bicycles
First of all, donor bikes need to be disassembled, and you can get a bunch of parts for the new assembly.
Rear bike preparation
It is necessary to unscrew the front fork and the handlebar from the rear bicycle. Even from the old frame it will be necessary to remove the cables, now they will not be needed. The bearing cage will also need to be removed from the steering cup. To do this, gently knock on it with a hammer. It is not fixed in any way; it is simply pressed into the steering glass.
Then a hacksaw is taken, and the steering glass is cut as shown in the photo. The result should be a "cup", it will surround the seatpost of the cyclist in front. That's all, now the back of the tandem is ready, you can proceed to create the front.
Preparing the front of the tandem
You need to remove the rear wheel from the bicycle, as well as cables, gear shifters and other equipment. Then a hacksaw is taken and with it all pipes that hold the rear wheel are cut off. How exactly this is done can be seen in the photo. As for the feathers, the upper ones must be removed, only the lower ones should remain.
Now, if you put two parts side by side, everything should look like in the photo.
Step Two Tandem assembly
What is the structure of the tandem can be seen on a simple diagram. Red color indicates the frame of the front bike, and the rear green. Special color is marked in blue devicethat connects the frames to each other.
According to the author, adhesive tape provides a fairly strong connection, if used in tension. But it is not powerless against shear loads, and also does not work on compression. The design of the tandem is such that the upper pipe moves in compression, and the lower, respectively, in tension. While riding, the cyclist presses on the pedals, and the lower part also starts to work a little on compression. Since only duct tape and crossbars will be used to create a solid structure, the task of combining bicycles together becomes more difficult.
To fix the frame in the upper part, just attach it with electrical tape to the seatpost. Tape must be tied carefully, the process resembles tying bamboo with a rope. As a result, the structure can move slightly forward and backward, however, it will not be able to bend.
Further, so that the frame becomes strong and does not bend in the middle, additional stiffening elements must be installed. The author for this purpose uses sticks that are attached with a large amount of electrical tape. Two sticks need to be attached to the upper tubes of both frames.
Then the sticks need to be tied to an articulation or seatpost, exactly how you can see in the photo. The shape of the tandem is determined by the height of the upper pipes.
It will be more difficult to make the joint at the bottom, as the chain will interfere here and there is nothing to tie together. To connect the structure below, the author uses the front fork, which was previously unscrewed from one of the bicycles. You need to remove everything superfluous from the plug, in the end it should become in the form of the letter U.
At the base of the U-shape, two notches of the V-shape must be cut. Thanks to this, the plug can be centered on the pipe to which it will be attached.
Then the fork is mounted around the seat tube, and its ends are fitted to the two tubes in front of the bike. When installing the plug, it is important to make sure that the chain does not hit it. If so, you will need to use a hammer to achieve the desired bend and unhindered passage of the chain. Well, then the front and back of the tandem are connected using electrical tape. First you need to fasten the fork at the ends in front, and then the plug can be wound to the seatpost. To achieve the greatest rigidity of the connection, you can wind up the electrical tape in other places where it is possible.
Step Three Final build phase
After assembling the frame, you will need to make a new chain for the bike, as it will be significantly longer. The chain can be assembled from two. The author has a chain length of 37 links. Since the frame can bend slightly, after assembly, the bike needs to be driven a little under load so that it takes its native shape.
It is also important to make sure that the pedals on the tandem are fully synchronized, otherwise, when riding, cyclists will kick each other. In addition, in the absence of synchronization it will be difficult to maintain balance, it will also be impossible to place the pedals horizontally.
Conclusion
That's all, the tandem is assembled, it has one gear and one brake in front. In order to connect the rear brake, you will need to purchase a long cable. Due to the fact that the weight will be large and the speed is high, one brake is definitely not enough.
Due to the fact that the design turned out to be not very strong and the tandem has weak brakes, the author has so far refused to use speeds. If we talk about numbers, then on such a simple homemade managed to accelerate to 56 km / h, which is not bad enough for electrical tape and a pair of sticks. Corporate tandem can accelerate to 72 km / h.It is simply necessary to choose one optimal gear, which must be used in the future.
As for the second wheel, it can be screwed on behind the saddle of the first bicycle, but it is best to do with one wheel, as the author believes that the presence of two wheels reduces the balance of the tandem. When the rear cyclist clings to the front, he bends along the corners with him, thereby achieving good balance.
As for the reliability and durability of the structure, of course the frame turned out to be quite flexible, it can bend under a load at an angle of up to 10 degrees. Despite this, the bike was actively operated by two guys weighing 83 kg for six months. The tandem also passed a cruel test, four guys sat on it at once, the total weight was 317 kg. The frame survived, the only thing that could not stand it was the wheel, it bent. So, according to the author, such a ridiculous and at first glance ridiculous design has the right to life.
Perhaps important!
The author used black tape;)
