1.5.1 Bicycle Chain
These chains transmit the power of pedaling to the back wheel (Figure 1.16). Most bikes use chain; a few styles use cog belts, but these are the exceptions. In the early stages of chain development, chain design grew in response to development in bicycles. Bicycles are categorized as shown in Table 1.7.
In addition to bicycles, these chains may be used in low-speed, light-load transmission operations, for example, in agriculture machines or with electric garage door openers.
Figure 1.16 Most Bicycles Use Chain
|Category||Models of Bicycles|
|General||Sports, small-tire, general-purpose, child's|
|Special Purpose||Road racing, heavy-duty carriage, track racing, mountain, tricycle, tandem|
Construction and Features
Bicycle Chains are generally categorized into two types: 1/2 × 1/8 and 1/2 × 3/32. The first number (1/2) is the chain pitch; the latter numbers (1/8 and 3/32, respectively) indicate the inner width in inches.
Number 1/2 × 1/8 chain is used for simple transmission without speed shifting; it has the same construction as Standard Roller Chain.
Number 1/2 × 3/32 chain is used with a derailleur. There are two types of construction—standard roller and bushingless (Table 1.8). In the bushingless chain, the inner link plates are extruded so that the inner plates also serve as the bushings (Figures 1.17 and 1.18). In most derailleur transmission chains, the link plates are bent or cut so that the chains can change smoothly on the front or rear sprockets.
|Nominal Number||Pitch||Inner Link Width||Construction||Application|
|1/2 × 1/8||12.7||3.30||Roller Chain||Simple drive
|1/2 × 3/32||12.7||2.38||Roller Chain|
Figure 1.17 Bushingless Bicycle Chain Components
Figure 1.18 Schematic Diagram of Bushingless Bicycle Chain
The basic sizes of the sprockets (front and rear) are common to all manufacturers; however, the tooth shape is different. This is especially true for the sprockets for 1/2 3 3/32 chains. Each manufacturer designs its own tooth shapes for better shifting. Exercise care when changing sprockets.
Selection and Handling
- Manufacturers usually offer a selection system for derailleur transmission, which includes the chain and sprockets. Check the manufacturer's catalog for information.
- The chain's performance is usually influenced by wear. Select a chain with specially coated pins, which increase wear resistance.
- You must connect the chains carefully, or they may break during operation. Use special connecting pins (sold separately) to connect chains, especially those used with derailleurs.
- These chains are frequently exposed to rain, dirt, or mud, which can lead to elongation or rust. The chains need regular cleaning and lubrication.
- Do not use weak-acid rust remover (such as phosphatic rust remover) on these chains. These chemicals can cause hydrogen embrittlement and chain breakage.
To keep up with the design enhancements of bicycles, chains are being developed in several ways:
- Lighter weight.
- Higher rust and weather resistance.
- Attractive appearance.
- Nonstaining to clothes.
- Lower noise at engagement.