What Type of Chain Do I Need for a 21 Speed?

A bicycle chain is a roller chain that transfers the energy generated by pedaling through the chain and onto a sprocket that propels the bike forward. The type of chain needed for a 21-speed bike can be found at any bike shop or large department store that sells bikes. Note the size and width of the chain before purchasing it to ensure that it is intended for a 21-speed bike.

  1. Width

    • A standard chain for a 21-speed mountain bike is 3/32 inches. You do not to put a chain narrower than this on your bike. For a mountain bike, you want the wider chain, because it is stronger and more supportive than a narrower chain. Mountain bikes endure a lot of rugged riding, and a wider chain holds up better in these conditions.

    Length

    • Bicycles with 21 speeds need 112 to 116 links on their chains. They tend to need more links because there are more gears to go around on the derailleur. The derailleur is the piece of hardware on the rear wheel that facilitates the changing of your gears. If you put the chain on your bike and it is too long, remove a few links from the chain with a chain breaker tool at the location of the master link. Initially, most chains are too long to ensure that the chain is the correct length for your bike.

    Material

    • Bike chains are typically made of alloy steel, a combination of metals. They can also be made out of stainless steel to preventing rusting. You need to replace your chain if it begins to rust or "stretches." Stretching is another word for chain wear, when the connectors that hold together each link become worn from extensive riding. This happens with all types of chains.

    Weight

    • The weight of 21-speed bike chains is typically 1 lb. Many riders try to reduce the weight of their bikes so they can ride faster; for example, having a carbon fiber frame instead of an aluminum or steel frame. You can reduce weight of the chain as well by spending more money on a higher quality metal chain. These are usually treated with a special coating that protects them from road dirt and dust.