What Are Steel Bushings?
Many makers of steel-bodied sports bicycles will tell you that they have invented new materials which do not contain any steel. That is not true. It is just that the term 'steel' does not have to be capitalized, as the name for a category of material that has a few other components in it makes a reference to a specific shape, such as a sphere.
When people refer to 'steel' as a material that does not contain steel, what they really mean is that the shape is one of several materials, with each component slightly different from the others, that makes the shape look like a sphere. So, for example, if a company makes a bicycle frame with a different shape of top tube than the bottom bracket shell, they would call that a 'shape'.
To get the stem and seat post of a bike upright, the top tube would need to be thicker than the bottom bracket shell, so that they could make an outward projection. So, when a bicycle frame contains no steel, it is called a solid-tapered or direct-riveted frame. The design of the headset may depend on the shape of the head tube, which requires using a steeper seat angle than some people prefer.
To help with the seating position, a part of the top tube can be longer than the seat angle and have a lower seat angle. The chain stays can be placed at an extreme or a low angle. This is known as 'polygonal'.
If it is possible to have components that are not joined to each other, it is also possible to have frames which are not attached to the bottom bracket shell. Those are called 'connective-tube'. In a similar way, a frame which is connected to the bottom bracket shell and at the same time has parts which are not connected to each other is known as a 'free-wheel'.
The three main components are fork blades, top tube and seat stays. The seat stays can either be free-wheeled or connect to the bottom bracket shell. The range of sizes and shapes in steel-bodied sports bicycles includes smooth-curved, 'L'-shaped, round-edged and triangular.
Steel is an alloy of iron and aluminum. It is one of the most popular materials used in bicycle making because it is lightweight, strong and resists corrosion. It is often applied to steel-bodied sports bicycles, and the main types of steel-bodied sport bicycles are the MTB (traditional mountain bike), the BMX (cycling with an obstacle course) and the BMX racing bikes.
Steels have their own advantages and disadvantages. They do not rust, but because of the strength of the material, the higher the weight, the less resistant the steel will be to rust. Steels are generally more expensive than carbon fibre composites, but for this reason they are more suitable for touring bicycles, where the bike is not likely to be used for heavy periods of time.