The bicycle chain is an indispensable part of the transmission that enables the bicycle to move. It converts pedaling energy into the rotation of the rear wheel. Without this component, the bicycle would remain stationary.

Each chain consists of links, which in turn include half-links, pins, and rollers. Despite the variety of models, all chains have the same pitch between half-links. Therefore, chain selection mainly depends on personal preferences and its thickness.

Structure of a Bicycle Chain

Except for Half-Link type chains, a standard bicycle chain includes the following elements:

1. Outer link plate
2. Inner plate
3. Roller
4. Bushing (sleeve)
5. Pin
6. Complete chain link
7. Gap for lateral bending

A chain link consists of two half-links connected by a pin inserted into a “sleeve”. A roller is placed on the pin, providing engagement with the sprocket teeth. The length of one link is 1 inch (25.4 mm). The total length of the chain is determined by the number of links.

For adult bicycles with 12 speeds, chains with 126 links are usually used. However, there are many variations – from 110 to 126 links. Mountain bikes (MTB) are often equipped with chains of 106 or 108 links.

If the purchased chain turns out to be too long, it can be shortened. This is done by disconnecting the lock (if there is one) and removing excess links. After adjusting the length, the chain is reconnected and installed on the bicycle.

Types of Bicycle Chains

There are four main types of bicycle chains, each with its own characteristics.

For Single-Speed Bicycles

This is the simplest type of chain, usually installed on budget teenage or children’s bicycles. They are designed only for bicycles with one sprocket on the rear wheel. These chains are highly wear-resistant as they are not subjected to the bends characteristic of multi-speed bicycles. They are made of thick steel with sturdy plates.

For Multi-Speed Bicycles

Used on bicycles with gear shifters. The main difference from single-speed chains is the presence of a gap for lateral bending. Their plates are thinner, which is due to the narrower sprockets on multi-speed bicycles. These chains often work at an angle, which accelerates their wear and the wear of the sprockets.

Lightweight Bicycle Chains

Can be used on both single-speed and multi-speed bicycles. Their feature is hollow pins and holes in the plates, making them 20-25% lighter than regular chains. Popular among racers where every gram of weight matters. However, such chains stretch, wear out, and break faster.

Half-Link Chains

A unique type of chain with a special design. Unlike standard chains, it consists of identical elements, without separation into inner and outer links. Suitable for both types of bicycles – single-speed and multi-speed. The advantage is the ease of fitting to the desired size of the bicycle. The disadvantage is rapid stretching and wear due to design features.

Main Dimensions of a Bicycle Chain

When choosing a bicycle chain, three main dimensions should be considered:

Chain Pitch

This is the distance between two adjacent pins. The standard pitch is ½ inch or 12.7 mm.

Chain Width

Determined by the size of the pin. The width varies depending on the chain’s purpose. There is an inverse relationship between the number of sprockets on a multi-speed bicycle and the pin width. Approximate ratio:

• 1 sprocket: 7-11 mm
• 4-5 sprockets: 8.7 mm
• 6 sprockets: 7.8 mm
• 7 sprockets: 7.3 mm
• 8 sprockets: 7.05 mm
• 9 sprockets: 6.6 mm
• 10 sprockets: 5.85 mm
• 11 sprockets: 5.5 mm

Length

The chain length depends on the manufacturer and bicycle model. It usually varies from 110 to 126 links. For mountain bikes (MTB), chains with 106 links are often used, for 29ers – 112 links, and for road bikes – 126 links. If the chain is too long and sags on the sprockets, it needs to be shortened.

Bicycle Chain Marking

Chain marking contains important information about its characteristics. For example, the marking ½”х3/16″ – 120 links Pinlength 7.3 mm means:

• ½” – chain pitch (12.7 mm)
• 3/16″ – width between inner links
• 120 links – number of links
• Pinlength 7.3 mm – external pin width

The width between inner links comes in four types:

1. 1/8″ – for single-speed bicycles, freestyle, and BMX
2. 3/16″ – rarely used, previously used on recreational single-speed bicycles
3. 3/32″ – common type for multi-speed bicycles with 6-8 sprockets
4. 11/128″ – for multi-speed bicycles with 9 or more sprockets

Sometimes the marking indicates the breaking strength (KGF), for example, 720 kgf, but this parameter is usually not given much importance.

How to Choose the Right Bicycle Chain?

When choosing a chain, pay attention to the marking containing the main characteristics. Many manufacturers use alphanumeric marking to indicate chain quality. As a rule, the higher the number, the better the quality.

Among popular bicycle chain manufacturers, we can highlight:

1. Shimano (Japan) – first to apply dry lubrication in chains
2. Campagnolo (Italy) – collaborates with sports cycling teams, produces high-quality but expensive components
3. SRAM (USA) – pioneers in the production of link locks
4. KMC (Taiwan) – offers chains close in quality to Shimano and SRAM, but at more affordable prices
5. Wipperman (Germany) – famous for high quality and reliability, but also high cost
6. Tyazhmash (Russia) – produces chains with increased wear resistance, withstanding loads up to 1100 kg

Chain Wear

Like any mechanical component, a bicycle chain requires regular maintenance, lubrication, and proper storage. To extend the chain’s lifespan, it is recommended to:

• Lubricate with special oil at least once per season
• Regularly clean off old lubricant and dirt
• When storing the bicycle for a long time (several seasons), remove the chain and store it in kerosene to prevent stretching and maintain appearance

The degree of chain wear can be determined by measuring the length of 24 links. The normal length is 12 inches (304.8 mm). Deviations from the norm:

• Up to 1.5 mm – normal condition
• 2.5 mm – replacement recommended
• 3 mm – possible gear shifting problems, urgent replacement required
• More than 3 mm – replacement of the entire transmission necessary

The bicycle chain is a simple but critically important element of any bicycle. In modern conditions, it is considered a consumable material, but the condition of the entire transmission depends on its state. To ensure long and reliable operation of the bicycle, it is necessary to carefully approach the choice of chain, its adjustment, cleaning, and storage.