The gear hub has a complete cable to guide and twist the shift handle, so it is easy to install on the bicycle. In addition, the width of the hub between the frame and the rear exit is roughly the same as that of the original single-tooth hub, so there is no problem.
In the second car, I installed a transmission hub. Because the backward width of the frame is only 120mm, which is quite standard for single-gear bicycles (some backward widths are only 1 15mm), I can only install a fifth-gear sprocket. Installing a sprocket and six or more gears requires at least a width difference of125mm. Please note that if the frame is made of steel, you can use a little force to restore the detached part at the back to the lost 5mm. If it is made of aluminum, you'd better leave it alone, just like mine.
I don't need to disassemble the wheel, I just need to disassemble the original single-tooth sprocket and modify the disk surface of the wheel to adapt to the larger width of the 5-tooth sprocket. I had to loosen all the spokes and then tighten them, so that the rims were in different positions. I also have to change the spacing between the hubs to keep the hub centered, although the spokes have different shapes (the whole hub has moved a few millimeters to the left).
Due to the new CD, once the hub is reassembled, the right spoke will protrude to the position of the rim and inner tube. So I had to file the spokes to prevent them from breaking through the protective belt and piercing the pipe.
Installing the transmission requires adding the transmission to the frame, which is easy to do, because these parts are usually installed on cheap bicycles. It also needs to install cables to stop to the frame, one near the transmission and the other near the steering, so that the cables can run along the frame without guide rails. Cable stops are not difficult to find because they use high-end aluminum and carbon fiber frames. I could have connected all the cables, but the channel turned out to be cleaner and better.
The most difficult thing to find is that one gear lever can operate five synchronous gears. This bike is for my wife. I hope it is very simple to use. I didn't find a twist grip, but I found an old mountain bike with a lever, which looked very beautiful.
Finally, I had to replace the chain with a gear suitable for synchronous transmission. In a word, I spent more collage and more parts to convert a geared bicycle transmission instead of another hub gear. In both cases, it is necessary to remold bicycle wheels. On the other hand, the transmission is cheaper to shift gears and the weight of the bicycle increases less.