Bicycle frame tube 

The frame tube of a bicycle is the main body of the bicycle, connecting the front wheel and the rear wheel to support the weight of the rider. 

The types of the shapes of bicycle frame tubes are quite simple. They are mainly divided into rhombic (rhombic box) and other shapes. 

Rhombus: 

1. Interlaced 

The installation position of the saddle on the upper pipe has been lowered and tilted. 

2. Double-ring type 

The interlaced top/bottom tubes are bent downward to further enhance the safety and convenience of getting on and off the vehicle. 

3. Parallel Type 

The upper and lower oil pipes are parallel. As a derivative form, currently many tubes are made into very thick oval or square single tubes. 

4. Hybrid type 

The entire pipeline from beginning to end. 

5. Circular Saw 

The sub-flow of the separator causes the upper pipe to bend downward, thereby further enhancing the ease of loading and unloading. 

6. H-type 

One type is that there is a thick single tube between the upper tube and the lower tube. When viewed from the side, the front fork, the single tube, and the seat tube form an H shape starting from the handlebar, with the performance advantage located in the middle, but the appearance is simple and lightweight. There are many single-tube products that can reduce the hinges, especially for folding bicycles. It is often used because the hinges are not too low and are suitable for the processing during the folding process. 

7. U-shaped 

The position of the single tube is lower than that of the H-shaped tube. The line from the handle to the lower tube and the seat tube is U-shaped. 

This is a teaching method for Chinese women and electric bicycles, focusing on the convenience of getting on and off the vehicle. 

8. L-shaped 

Straight section, featuring an extended U-shaped base. The key features are the expansion of the wheelbase and the stable design. 

The names of various tubes in a bicycle frame 

The pipes that form the diamond-shaped framework are separated in the following manner. Each pipe is joined together through a combination of welding or bonding (＜"lagging" ). 

Pipe jacking 

Also known as the upper tube or upper tube. It is the tube that connects the head tube and the upper end of the seat tube. 

2. Head tube 

Also known as the head clamp or head tube. The head is clamped at the top and bottom of the tube, and the steering column of the front fork passes through it. 

3. Lower the pipe 

Also known as the lower pipe or the lower connection pipe. The pipe connecting the head pipe and the lower end of the seat pipe. 

4. Seat Manager 

Also known as vertical pipe or vertical tube. It is the pipe connecting the upper and lower pipes. The valve stem of the seat is inserted into the tube from above. 

5. Bottom support housing 

Connect all three pipes at the intersection of the lower pipe, the seat pipe and the chain. This part (component group) is called the bottom bracket. 

6. Seat Stay 

Also known as the "back eagle". The pipe connecting the upper end of the seat tube and the rear axle. There is a couple on each side. The left and right valve seat pillars are connected by a single short pipe. This is called the "base bridge". The method of fixing the front end to the upper tube is called the "cross plate seat". There is a hole for fixing the caliper brake in the proper position. 

7. Chain Accommodation 

The tube connecting the lower end of the seat post and the rear axle. There is a pair on each side. The left and right chains are connected by a short tube. This is called a "cantilever bridge", but it can be omitted according to the frame structure. 

8. Front fork 

Also known as the "front fork". The front fork fixes the front wheel to the frame to reduce the impact on the road surface. Although it is not fully incorporated into the frame, for convenience, it is usually analyzed and treated as a part of the frame only on Chinese road cycling bicycles.